Vestigial Characteristics: Monkey Features of the Human Newborn

Newborn babies arrive with some pre-installed software and hardware that demonstrates, beyond a shadow of a doubt, our primate heritage.

Vestigial features like Darwin's point (see post below) evoke the pointed ears of Old World Monkeys — the ancestral line of nonhuman primates from which human primates descended. Old World Monkeys have pointy, Spock-like ears. You can see them perfectly in the photo of the baby saki monkey at the right.

The ears of Baby Field Notes have this point, named after Darwin because he was the first to observe and write about it. The arrow in the photo shows where she also has a tuft of hair growing from her ears. Right now the hairs are about 1/2 centimeter long. Like the hair growing on her shoulders, this hair will thin out with age.

Perhaps you can feel a small bump along the rim of your ear. Feel along. Not everyone has one that is pronounced and if so, it is often only present on one side. That little bump is a relic of your ancestors' descent from monkeys. So is the shoulder hair and ear hair of the newborn human primate.

In fact, humans are just as hairy as other primates, including other apes. We have just as many hairs per square inch as chimps, gorillas, bonobos and orangutans. Ours are just so fine and so short that they appear to be invisible, thus giving humans their 'naked ape' label. We're not really naked and hairless at all. Look closely at your skin under good lighting the next time you get out of the shower and you'll see what I mean. Our faces are hairy too.

As for pre-installed software, newborns have a number of reflexes that would clearly have been evolutionarily advantageous. One, the Palmer grasp, wold have been useful for grasping onto mom's hair in an emergency if she had to move abruptly. Newborns can actually support their own weight with it. I am not willing to experiment with BFN, but you can see in the following video exactly how impressive this reflex is.

Palmer Grasp Reflex

The Palmer grasp can be seen in human newborn feet as well.


The Moro reflex is another reflex useful for keeping baby with mom when she moves. Other primates occasionally hold their babies when they move, but for the most part, nonhuman primate babies latch onto mom's hair on their own and can stay in contact with her while she moves even when mom doesn't provide support. Humans retain these reflexes in spite of not being able to take advantage of them. They are atavistic, vestigial traits. These reflexes, like the presence of a nonfunctional appendix, illustrate that not every trait that is a product of evolution has a function in its present form.

Moro reflex

Baby Birth Announcement: It's a Gorilla!

(Credit: San Francisco Zoo)

A baby gorilla who was born 6 months ago at the San Francisco Zoo has started making some appearances now that he's old enough.

He is way too cute. I don't think there's anything in the world cuter than a baby gorilla, that's my bias. Maybe my own little baby 'gorilla' will be cuter, but I doubt it. Is that mean? What can I say, I am biased I admit it: I love baby gorillas.

As with most zoo birth stories, this little bugger was rejected by his birth mama but another female stepped in to care for him. She carries him on her back in the customary "jockey style" position. The babies ride face-forward sometimes, other times facing the reverse direction. Whatever feels good and works. Having hair makes it easy to hang on to mom, giving her the ability to move around more or less unencumbered, unlike human moms who must use at least one arm to support a baby she carries.

Even though human ancestors lost their hair a long time ago, for whatever reason — it's still a mystery even though there are some interesting theories — human babies have retained the moro reflex.

Babies up to around age 4-5 months, in response to being startled by a loud noise or falling sensation, will extend their legs and arms with hands open then bring them back to their body with their fists clenched.

It's an obvious safety mechanism left over from the days when that sort of automatic response would have helped the baby grab mom's hair in an emergency - having to quickly flee a spot, nearly falling out of a night nest up in the trees, etc. I don't know for sure since no one really makes a big deal of studying such obvious things, but I'd bet all primates have this reflex as newborns.

The absence of it in humans, or presence of it but only involving one side of the body, is a sure indicator of neurological problems.

There are lots of other cool reflexes babies have only during their first few months of life. I'm looking forward to seeing them.

And, yes, I am a little envious of the whole gorilla-baby-can-hang-on-to-mom-but-human-baby-can't thing. It means I'll have to find a sling to wear if I want to have both hands free. Ideally, I'd have one I could use to nurse hand's free. Gorillas don't have to wear diapers either...
I'm just saying. Not really looking forward to that end of things. But, I have smelled gorillas, and as much as I love them, holy man alive - they freaking reek!

Let's just say they have a distinctive odor. But they are still the cutest little beings on the planet. Little Hasani, whose name means 'Handsome,' even has a baby registry at the zoo in case you want to send him stuff.

You've got to see the video of him with his surrogate mama for the first time. You can see her playing the airplane game with him - putting him up in the air with her feet and hands while she lies on her back. Chimps do this with their babies too. It aids motor development. There's a lot of continuity among species in early primate development.

Mama Gorilla Plays Airplane Game With Baby Gorilla

Why Expectant Dads Gain Weight Too

When it happens to humans, it's called 'couvade syndrome' as if it was some sort of illness. But the bit of extra weight an expectant dad puts on during his mate's pregnancy may not be a sick psychosomatic reaction at all.

A group of primate researchers who study two very unique species — common marmosets and cotton-top tamarins — noticed that males mated to pregnant females gained between 2-20% extra weight during her pregnancy.

The only other primates species reported to gain weight during their mate's pregnancy are humans.

In one study of couvade, derived from the French ‘to incubate or hatch,' 47% of the 81 expectant fathers in the study experienced significant weight gain during their partner's pregnancy. They also reported nausea, headaches backaches, restlessness, and anxiety. The medical and psychological community believe these to be sympathetic reactions to a mate's pregnancy without a biological cause, but perhaps there is one.

According to primatologist Toni Ziegler and co-authors, expectant fathers might be preparing for the energetic cost of fatherhood by gaining weight during their mate's pregnancy. But why?

Tamarins and marmosets are unique among primates for their high degree of male parental care.

Females give birth to twins that can weigh as much as 20% of their body weight, which for me, would be like giving birth to not one, but TWO babies that weigh 12 pounds! That's a lot of weight to haul around. Primates carry their babies with them either on their bellies or their backs wherever they go. Sure, a few oddballs (bushbabies) stash them in tree holes, but the vast majority of primates carry the babes more or less constantly. Baby-wearing is not some new trend among celebrity people, it is an old, old custom.

What makes tamarins and marmosets especially unique is that the dads carry the babies — not the moms. Moms just nurse them. It's the dads who do the heavy lifting. Thus, it makes good evolutionary sense for them to bulk up. They'll be burning a lot of extra calories packing around twins wherever they go so having a good supply of fat laid down in advance helps. Moms gain weight too, of course. Nursing is also energetically costly.



Pregnancy weight gain: marmoset and tamarin dads show it too. (2006) Ziegler et al.

P.S. Dear Mr. Field Notes, if you're reading this it's okay to hog the peanut butter cookies, just save some for me and expect to pitch in with baby carrying =D

Birth of a baby orangutan

I was going to post on an orangutan who has figured out how to whistle, but the video commentary was inane, and this video of an orangutan giving birth is really neat. I imagine some might find it kind of gross though. After all, she eats the placenta and sucks her baby's head to clean him.



I can't help but to wonder when during human evolution we stopped licking our newborn babies. I've heard some cultures still do this. This sort of grooming also reminds me of some really cool research on mice that found that this initial licking and grooming postpartum is essential for normal physiological development. It kick starts digestion and lays the foundation for how the baby's HPA-axis functions later in life.

The HPA-axis, or hypothalamic-pituitary-adrenal axis, refers to the nervous and endocrine system that regulates the physiological response to stress. Rodents that don't receive early grooming grow up to have abnormal reponses to stressors; namely they release too much cortisol under duress.

Chronically high levels of the hormone cortisol have been shown (including among humans) to be associated with a weakened immune system, depression, and brain atrophy. That's really putting into a nutshell what I learned in what may be the most freakishly awesome seminar I took during grad school: Psychoneuroimmunology, or PNI.

If you would like to learn more about how behavior, mood, hormones and the nervous system interact to affect your health I highly, HIGHLY recommend the book Why Zebras Don't Get Ulcers by Robert Sapolsky. Although he is as mega-scientist who professes at Stanford, the book is as readable as it is fascinating and entertaining. I freaking loved this book! Of course, he's also a primatologist and he has a wicked sense of humor. His other books are fantastic too, by the way. You cannot go wrong.

I still remember the day back in grad school when I was in the mail room and a fellow (newbie) grad student (who came to study PNI specifically) saw the book sitting on the counter and made some snide remark about how he hated it when laypeople jumped on the stress/immune system bandwagon and didn't know what they were talking about. It was then that I decided that he was an arrogant, ignoramus little snot. He had no clue who Robert Sapolsky was. Maybe Mr. Sapolsky shoulda put his big PHD behind his name on the book cover. In any case, I got the last laugh that day. I don't even know why I even still remember that, honestly, but it evidently made an impression.

Birthing a hyena — OUCH!

Sit down for this one!

I never knew much about hyenas until I discovered them in a book I highly recommend to anyone who wants to learn more about evolutionary psychology, primatology and motherhood from a female's perspective. It's called Mother Nature, by researcher-primatologist extraordinaire Sarah Hrdy. In the book she describes how hyena moms give birth. It was a real eye-opener to say the least.

From birth hyenas — a female dominant species — get super doses of male hormones. This primes them for the aggressive lifestyle they lead but also has some bizarre side effects. Namely, their genitalia are masculinized: the clitoris grows to male proportions of around 7 inches long, making them literally look like males. Researchers have great difficulty telling them apart from actual males. But what's more — I hope you're sitting down — they give birth through it.

Yep, that's right. They give birth through what amounts to a penis! The opening is only about an inch wide and babies weigh roughly two pounds — large enough to cause problems. Moms' tissues frequently tear during delivery and maternal and infant death is common, especially among first-timers. Some babies suffocate to death during delivery.

Females also mate through through the organ — giving the guys a difficult task as they try to position themselves just right. Apparently it takes male years to perfect the positioning to be successful.

If you'd like to learn more about sex role reversal and social dominance among hyenas, this article is a good, brief introduction: Establishing dominance.

The Price of Walking Upright

Oh to be a monkey in about 4 months instead of human... things would be so much easier, specifically giving birth.

Labor and delivery is not something I used to think a lot about, outside of the day I spend with my primate behavior classes talking about it. We discuss the impact of skeletal and pelvic bone arrangement on labor and delivery in my unit on bipedalism. They are often amazed when I tell them other primates give birth in about 30 minutes.

Walking upright is a major adaptation on the part of humankind so it's only fitting to devote a good amount of discussion to it. I think it's a really fascinating subject, not just because the transition from 'knuckle walking' to walking on two feet required major changes to the arrangement of bones that made human childbirth incredibly dangerous — and painful — but also because no one yet has any convincing and widely accepted explanation for what drove the shift to bipedalism in the first place.

Was it that our hands we free to carry food, tools, a baby? Who knows. Some think we stood up because it kept our bodies cooler while walking long distances in the African savanna to find food. There are at least 6 other unique theories out there and whatever the explanation — the cost is significant.

The human pelvis became shorter and broader and the opening in the bones, the birth canal through which a baby passes during delivery, took on a more oval shape. The fossil, Lucy, one of the first skeletons to show signs of upright walking, resembles a modern human pelvis more than a chimpanzee's. The shift meant that babies, including ancestral humans, had to turn sideways during delivery rather than coming straight out like other primates.

When other primates give birth, the babies come out face up, more or less looking right at mom. Mom can see the baby the whole time and guide the little guy out all on her own. Not so for humans. If a human mom were to try to pull her baby out on her own, the angle of the head and neck would be off enough to potentially break. The shape of the human pelvis is great for walking, but very bad for solo delivery. It's believed that humans have always had to have a helper during delivery.

Another unique development that made birth difficult for humans is our large brain. Psychologists and evolutionary anthropologists call this 'encephalization.' Based on fossilized skull remains, our craniums and brains appeared to get significantly larger right around the same time we started walking on two feet.

In most cases, the baby's head is larger than the birth canal and without flexibility, the baby couldn't be delivered successfully, and either baby or mom — or both — would die. Even now with modern medical approaches to childbirth, a significant proportion of babies are delivered surgically through C-sections because the baby's head is too large.

Without some modification through evolutionary processes the human species, with it's unique gait, would have gone extinct. Two adaptations worked against this:

• relaxation of ligaments that hold together bones of the pelvis, hips and back

• gaps in the baby's skull

Both ultimately helped make birthing big brains possible. The 16-30 hours of labor are just one cost. In contrast, other monkeys (with a few notable exceptions) and apes give birth in about 30 minutes!


Although that may sound idyllic, it's not something I or any other pregnant woman is ever going to experience. But we can be very thankful that human birth and labor is not nearly, not even remotely as awful as what female hyenas endure. More on them next time... It will blow your mind!

Cucumbers & Morning Sickness by Design

Cucumbers must have some highly toxic components because they continue to be a food that smells absolutely disgusting to me. Unfortunately, someone who sits near me at work loves them. Fortunately though, the scent aversion is all part of the mind's design — a pregnant mind.

Morning sickness, or rather pregnancy sickness for it truly occurs at any time of day, appears to be a bona fide adaption in an evolutionary sense. It's adaptive, meaning it is helpful for us as a species, but more than that, it is an adaption — a mechanism with enough complexity, precision, and efficiency to indicate a functional design.

Long, long, long before I ever became pregnant I read Margie Profet's landmark research on the evolutionary significance of morning sickness and was impressed enough to remember that although it is seriously annoying — it is actually a very good thing to experience while pregnant. It means the baby has a higher chance of being healthy and a lower chance of miscarriage.

What I didn't recall, until I recently reread the paper, is that the evidence is actually quite impressive. I also learned that the author herself is impressive. Having never formally studied biology or evolution and with only a BA degree — and a brain — she scored a $250,000 MacArthur Foundation Genius Grant to study the phenomenon. Freaking awesome! And jealous! I could have spared myself all those wasted years slaving away in grad school... grrrr. However, they did land me a couple of killer teaching positions!

So, McGenus Profet accumulated the evidence that showed that the nausea, food and scent aversions, and vomiting associated with the First Trimester of pregnancy represent an adaption. Previously, it had been thought that it was all a sickness, a side effect of pregnancy hormones with no benefits, only costs. And, those costs are significant. Women who experience pregnancy sickness can experience weight loss and inadequate nutrition from avoiding and/or throwing up nutritious though unpalatable foods. But there is a method behind the months of madness.

Evidence pregnancy sickness is an adaption

• Many foods contain compounds that can produce malformations, sometimes fatal ones, in developing embryos.
• Women who have pregnancy sickness selectively avoid foods that indicate those toxic components are present.
• The onset of pregnancy sickness coincides with the time the embryo becomes vulnerable to the toxins.
• Pregnancy sickness ends when the embryo's need for calories for growth outweighs its vulnerability to the toxins.
• Changes in the olfactory system of a woman who has pregnancy sickness cause her to avoid substances with those toxins. Basically, a more sensitive sense of smell and lowered threshold for finding scents disgusting help a woman avoid foods that could harm the developing baby.
• Finally, and most important for establishing pregnancy sickness is adaptive, women who experience moderate to severe pregnancy sickness have greater pregnancy success rates.

Cool beans if you ask me! The part I forgot was the 'sickness' ending when the fetus isn't as vulnerable as it is hungry.

So the list of no-go foods? The article pointed out that celery, cabbage, cauliflower, brussels sprouts, bananas, oranges, apples, potatoes, soybeans, black pepper, cocoa and nutmeg (among lots of other foods, especially green, leafy veggies) all have compounds that are known carcinogens. Although they are in small enough quantities to be safe for adult consumption, they are harmful to a fetus.

So glad, in way, to have experienced the morning sickness phenomenon! Equally glad, if not more so, that it is going away!!

Heartaches are heroes when their pockets are full

One of the classic studies from Evolutionary Psychology, one that gets mentioned in all the textbooks and is known to all students of the field, perfectly illustrates a line from the Rosanne Cash song Seven Year Ache: Heartaches are heroes when their pockets are full.

It's best known as the "Burger King study." The researcher, John Marshall Townsend, an anthropology professor at Syracuse University, dressed the same man in two different ways. One was a Burger King uniform, and the other was a white shirt with nice tie and watch and a navy blazer. He had women look a photo of the man and evaluate to what extent they would: like to have coffee with him, date him, have 'uncommitted sex' with him (a favorite question of EP), have a serious involvement with him, have a serious sexual relationship, and marry him (another favorite EP question). Unsurprisingly, women across the board rated the nicely dressed man higher.

Perhaps a better song and line to pair with it is ZZ Top's Sharp Dressed Man: Every girl's crazy 'bout a sharp-dressed man.

The real question then becomes why? Why do women prefer a sharp-dressed man. Ah, sure, women want a good provider. But why? The answer depends on who you ask. Ask an evolutionary psychologist and they'll tell you it's because ancestral women who chose men to mate with who showed signs of status and wealth left more offspring than women who were indifferent to wealth. Ask a member of the "Flat Earth Society," what some evolutionary psychologists call women's studies departments, and they'll say it's because women learn to prefer wealthy men because that's what our culture values. I say it's what our culture values for a good reason: Those values helped us thrive as a species.

The need for women to prefer wealthy men has a lot, I think, to do with the ecological conditions women have customarily faced, namely, lower status. Another significant one is having babies that are metabolically costly and also incredibly difficult to care for, compared to other species. Human babies are basically born before they should be. They come out of the womb much less developed and far more dependent on mom than other primate babies, including other great apes, who also have very dependent babies. Human babies require significantly more care and that is made a lot easier with the help of another parent who can provide food, shelter and protection. The higher status the helper, the better fed the baby and the more likely to survive. That's how the theory goes.

There are some feminist evolutionary psychologists who doubt whether that helper actually was a male sexual partner. The other helper (or helpers most likely) could have been a mother, grandmother or other females raising babies cooperatively.

Pygmy tarsier, a monkey that defies categorization, not extinct afterall!

With a tail like a rat, sticky fingers like a gecko, frog-like legs, a head that rotates all the way around like an owl, bat-like ears and the plump face of a baby, the tarsier definitely counts among the most bizarre animals on earth. And it's also a primate! The smallest kind of tarsier was believed to be extinct until it was found last month on the Indonesian island of Sulawesi.

Sometimes called the world's smallest monkey, the pygmy tarsier is neither a monkey nor even the smallest primate. The tiny dwarf lemur of Madagascar gets that honor. And, primatologists say the tarsier falls somewhere between the prosimians (lemurs, busbabies) and monkeys on the evolutionary scale. They are not quite monkeys, but not quite prosimians either. They have qualities of both. One classification system puts them with monkeys, another with prosimians, but yet another gives them a category all their own. I like that one best. A unique creature should gets its own special spot.

Tarsier traits in common with lemurs, busbabies and other prosimians:

• grooming claw: This is a sharp nail, usually just one on each hand or foot, and often only on the hands or the feet. It's used for keeping clean.
• bicornate uterus: Rather one pouch for growing babies, these guy have a uterus that is V shaped, providing two pouches. This makes it much easier to have more than one baby at a time, though like monkeys, tarsiers usually one have one baby at a time.
• two pairs of nipples: Only the top set is functional. The other is vestigial and doesn't produce milk.
• small body size: Prosimians tend to be noticeably smaller than monkeys and apes.
• nocturnal: Tarsiers are creatures of the night. They have the large eyes to prove it too.
  

Tarsier traits in common with monkeys:

• no tapetum: The tapetum is a layer of the eye that reflects light. It helps nocturnal animals see better in the dark by amplifying light. When animal eyes glow at night when light hits them, it is the tapetum you're seeing. Monkeys, apes, and tarsiers don't have a tapetum. Tarsiers lack a tapetum even though they are nocturnal which suggests that tarsiers may have once been diurnal and became nocturnal in response to some change in their ecology, for example, the addition of new predators or competitors. They now occupy the same ecological niche that owls do.
  
• dry nose: Monkeys and apes belong to the group called 'haplorhines' as opposed to the 'strepsirhines' or wet-nosed primates (the prosimians). Tarsiers have dry noses.
• central fovea: The part of the eye's retina used for high-acuity and color vision.
• reduced olfactory bulbs: A part of the brain specialized for processing scent. Prosimians communicate with smelly secretions much more than monkeys do. Scent isn't totally irrelevant for monkeys and apes, it's just that visual and vocal communication take precedence. Perhaps this is because at night, when most prosimians are active, it is either impossible to communicate visually or downright dangerous to communicate out loud. Singals may not be seen through the dark of night or may be heard by predators. It's much more stealthy to communicate with scent.
• flexible upper lip: This greater freedom of movement, due to more as well as more complex muscles, allows monkeys and apes to make facial expressions. This is one of the big reasons why people see reflections of humanity in their primate relatives. The look of joy, boredom, anger and more can all be seen displayed on the faces of monkeys, tarsiers included.

Anthropologist Sharon Gursky-Doyen of Texas A&M University found the presumed lost species in the mountains of Sulawesi Island. It hadn't been spotted in the wild for 80 years.

"They always look like they have a perpetual smile on their face, which adds to the attraction," she said in an interview. To me, they look almost exactly like Furbees, that fuzzy, robotic toy that was insanely popular about a decade ago. I think even my grandma had one.

The cute yet enigmatic little primate, neither monkey nor proto-monkey, weighs a mere 2 ounces and eats mostly insects. They are also known to eat snakes.

Sisterhood is Powerful: Lessons from Gelada & Hamadryas Baboons

Living along the cliffs of highland Ethiopia is a fascinating species of baboon called the Gelada baboon. They are magnificent creatures and stand apart from the rest of the primates due to their chests. They are bare and bright red.

Both males and females of the so-called bleeding heart baboon have hourglass shaped areas of bare, red skin on their chests. Female geladas, upon reaching sexual maturity, develop blister-like bumps around the edges of these skin patches.

They swell and change color from whitish to red in conjunction with the female's estrous cycle. They are an obvious indicator of fertility, somewhat like the fleshy rump patches of other baboons, chimps and bonobos.

Because gelada baboons spend most of their day sitting on their behinds munching grasses, they don't signal ovulation on their rears like many other primates do. What good is a hidden signal? So it's displayed where it can be seen — on their chests. Some evolutionary psychologist think something similar drove the evolution of human female sexual signals. Instead of sporting swollen labia like chimps and bonobos do when they ovulate, human females have a much more subtle signal in the form of a different pair of red lips. The ones on our faces. It's a much more subtle signal. No wonder men find women mysterious!

Gelada baboons live alongside steep cliffs. At night, they climb down the rocks to sleep, safely away from predators. They huddle together for warmth. Nights in the mountains of Ethiopia are chilly. Males and female have evolved thick fur to cope with the conditions. Males have especially thick hair concentrated around their heads, neck and chest. They look very much like lions. It is said that Ethiopian warriors use their manes in traditional costumes.

Their unusual appearance and striking presence is one thing, but perhaps the most interesting aspect of these primates is their social structure. It is one of the most complex among primates and is often cited as a model for understanding what the social structure of ancestral humans might have been like.

Gelada baboon social structure is also especially interesting because it contrasts sharply with a closely related species of baboon — the hamadryas baboon. Both species of baboon live in Ethiopia in the highlands in groups of hundreds of individuals. Bands upwards of 400 have been spotted in one place, but they recognize only the few who live in their troop and especially their harem. Harems are formed of 2 to 8 females, their young and one dominant male. Sometimes harems are referred to as OMUs or one male units to differentiate their social system from that of human harems, but the concept is basically the same. Often, gelada and hamadryas baboon harems have a hanger-on or follower male who is too young, too inexperienced, or too low ranking to acquire his own harem. And that's where some of the stark differences between the two species can be seen.

Hamadryas males actively herd their females using visual and vocal threats. Sometimes they bite. A nip to the back of the neck corrects wayward females who may be intent on defecting to another harem or joining up with a follower male. It can get vicious and stressful from a female's point of view. Hamadryas follower males also try to steal the females — even females that are juveniles not yet mature enough to reproduce. They kidnap the youngsters and guard them until they are old enough to mate with. They do take good care of their young charges by grooming them, helping them up and down cliffs, and watching out for other signs of danger.

Gelada females, in contrast, have much more relaxed lives. Males don't herd them or try to abscond with them or their babies. They live lives characterized more by sisterly bonds than domestic abuse. Gelada females enjoy very tight bonds with other females in their group, spending most of their grooming time on each other. In contrast, their hamadryas counterparts focus most of their grooming on 'the boss.'

Why do gelada and hamadryas females live such different social lives?
The answer is actually remarkably simple: Gelada females are family. Hamadryas females are totally unrelated to each other. Kinship is a powerful determinant of behavior among primates.

Why are gelada females all related to one another?
At sexual maturity, when juveniles complete puberty and become capable of reproduction, they must leave their natal troop, their birth troop, to avoid inbreeding. Among geladas, it's the males who leave. For hamadryas, it's the females who leave. When they join new troops, they find themselves living with unrelated females who are more interested in the dominant male than each other. For gelada females it's just the opposite.

Are the bonds of sisterhood powerful deterrents for male violence? I think the story of the gelada and hamadryas baboons suggests so.

Parenthood: Males need not apply.

We've all heard stories of the "Virgin Mary" but did you know that in the realm of science it is actually possible for some species to become pregnant without having sex? Of course you have!

It's called 'asexual reproduction' and many simple species reproduce this way — bacteria, fungi and many plants. We just don't tend to see many female animals reproduce asexually, without the assistance of a male's DNA.

The Journal of Fish Biology reports that scientists have proof, through DNA testing, that a shark has managed to conceive without the help of a male - or even another female for that matter. It's not even the first time asexual reproduction has been documented in sharks either. The first known case occurred with a pup born to a hammerhead shark at an Omaha zoo years ago. The poor little thing got munched though — by the other sharks in the tank.

This newest case comes from a female blacktip shark at the Virginia Aquarium & Marine Science Center. Her tank never contained a male shark, yet she was carrying an almost full-term fetus when she died. As it so happens, pregnancy is risky for sharks just as it is risky for people. She died from late-term pregnancy complications, determined through an autopsy. The pup she was pregnant with died too. His DNA was analyzed — it contained no genetic material from a male — proof positive of parthenogenesis, asexual reproduction.

This so-called 'virgin birth' has been documented in some amphibians, reptiles, bony fish and birds!

What happens during conception via parthenogenis is that the newly forming cell acquires an extra X chromosome when the mother’s X chromosome duplicates itself during egg development. I found this graphic that sort of explains it visually, for those already familiar with normal meiosis.

The resulting offspring is always a female, unlike with asexual reproduction in birds which can result in male offspring because female birds carry an X and Y chromosome. I've always thought that was pretty cool about birds, and I suppose that means that means that female birds are the ones likely to show sex-linked traits like human males are more likely to express color blindness if the gene is inherited. But, back to the sharks — a shark mother only has X chromosomes to contribute, so 'virgin' conceptions alway result in a female.

Without the chromosomes provided by the other sex, the offspring of asexual reproduction have reduced genetic diversity — a major disadvantage. The greater genetic diversity produced by sexual reproduction (two parents) is significant. For one, it creates a healthier immune system — one that is able to recognize and kill off a wider variety of pathogens.

However, the ability to reproduce asexually can also be a significant advantage. If, for whatever reason, the sex ratio (number of males to females) becomes skewed, a females might not be able to find a mate to reproduce with. If she can reproduce without a male - the species may continue to live — but only as long as females can continue to reproduce asexually. If they can, the number of females will continue to rise, remember, because they can only produce other females. The sex ratio will then become even more skewed, making it even more difficult for the remaining females to reproduce sexually. Eventually, the population will plummet. This is likely to be the case when pathogens and congenital malformations are present.

The scientists, during interviews about their research which was picked up by the AP (how I found out about it) cautioned that these rare asexual births should not be viewed as a possible solution to declining global shark populations. And, now you know why =D

Are you a throwback? Check your ear.

When I was a kid I was totally fascinated by this little bump on my right ear. If I feel the outside of my ear, along the edge, I can still feel that little bump. Maybe you have a little cartilage there too. Do you?

It's called Darwin's point and is a relic of our mammalian past.

The heritable trait runs dominant, which means if either of your parents gave you a gene for the point, you'll express the trait and have a little bump on your ear too.

According to the article "On the Pithecoid Type of Ear in Man" published in 1899 by the Zoological Bulletin, half of men and one-third of women have one. Several decades before, when the pseudoscience of phrenology was all the rage, people thought the trait was associated with criminality. It's tied to criminal propensity as much as it is to the appendix, which is to say — not at all.

Scientist: All Blue-Eyed People Are Related

.. from FoxNews.com. My commentary follows.

If you've got blue eyes, shake the hand of the nearest person who shares your azure irises: He or she may be a distant cousin.

Danish researchers have concluded that all blue-eyed people share a common ancestor, presumably someone who lived 6,000 to 10,000 years ago.

"Originally, we all had brown eyes," Professor Hans Eiberg of the University of Copenhagen said in a press release. "But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a 'switch,' which literally 'turned off' the ability to produce brown eyes."

That "switch" — a simple change from "A," or adenine, to "G," or guanine, in the DNA — actually sits next to the OCA2 gene, which regulates the pigmentation of our eyes, hair and skin, and hence has only a limiting effect on it.

If the mutation had completely deactivated OCA2, all blue-eyed people would be albinos.

Eiberg and his team analyzed 155 individuals in a large Danish family, plus several blue-eyed people born in Turkey and Jordan.

All blue-eyed subjects had the mutation, and there was very little variation on the genes neighboring it on the chromosome, indicating that the mutation first arose relatively recently.

In contrast, most mammals share the "normal" form of the gene. The six-letter sequence is exactly the same among mice, horses, cows, rats, dogs, cats, monkeys, chimpanzees and humans with brown eyes. (No word on what gives Siberian huskies and Siamese cats blue eyes.)

Eiberg figures the mutation took place on the northern of the Black Sea, but that's an educated guess, assuming the first blue-eyed humans were among the proto-Indo-Europeans who subsequently spread agriculture into western Europe and later rode horses into Iran and India.

Ironically, neither the first person to have the mutation, nor his or her children, would have had blue eyes themselves.

Blue eyes are a recessive trait, and the gene must be inherited from both parents. (Green eyes involve a related but different gene, one that is recessive to brown but dominant to blue.)

It wasn't until the original mutant's grandchildren or great-grandchildren hooked up — cousin marriage is the norm through most of human history — that the first blue-eyed person appeared. He or she must have looked pretty odd for the Neolithic era.

Eiberg stresses that the genetic variation, as the press release puts it, is "neither a positive nor a negative mutation."

That's a bit disingenuous, as the mutation also produces greater instance of blond hair (sexually selected for even today) and fair skin, which confers a survival advantage by stimulating greater production of vitamin D in sun-starved northern European countries — exactly where blue eyes are still most prevalent.

• Click here for the full journal article.

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If the author stressed that the blue eyed mutation is "neither a positive nor a negative mutation," then why did the journalist then contradict the scientist?

Grr. If I had been the editor I would have corrected the author. The mutation does NOT produce blonde hair and pale skin. Correlation is not causation. It just so happens that those traits co-occur.

What else is interesting about blue eyes is that they arouse suspicion in some parts of the world — Turkey and Jordan included. Cultures across the Mid East and North Africa believe blue eyes are the source of the evil eye. They have the power to dry up a mother's milk. When I was in Tunisia I saw one blue-eyed person the entire time. He was so remarkably different that I actually blurted out loud to him "Vous avez les yeux bleu!" He responded "Yes! Yes! Blue eyes" and pointed out mine. It was cool, and memorable.

I could imagine that blue eyes are indeed a sexually selected trait like some evolutionary scientists think blonde hair is. Perhaps there is some truth to the "What is exotic is erotic" idea. Who knows.

But, I definitely want to read the original article!

Orangutan Pastel

Here's my second attempt at a pastel - an adult male 'cheek padder' orangutan. I worked from a photo of an individual I believe is named Adik. Adik lives in Borneo and as you can tell from his cheek phalanges, he is a dominant male.

In Borneo, only dominant males develop secondary sexual characteristics such as full cheek pads, deep voice, and a huge size. Subordinate males who live in the dominant male's territory do not develop these traits. No knows quite why the so-called 'Peter Pan' males fail to develop. It may be stress-induced dwarfism or hormonal suppression possibly caused by pheromones emited by the dominant male. If the dominant male leaves or dies, the most dominant of the subordinate males in the area mature and become the dominant male with all of the associated physical characteristics. Orangutans are the only primate known to display two different coexisting adult male morphs. Of course there's a scientific term for it. It's called bimaturism, but some also call it arrested development.

Besides being physically stunted, the Peter Pan rangs might also be considered socially stunted. Females prefer to mate with the dominant males, so in order for subordinate males produce progeny they often resort to alternative strategies: rape or what primatologists call forced copulation. Females have evolved strategies for dealing with the threat of forced copulations. Lone females will travel to be closer to a dominant male. If she can't find one she seeks out other females. When no dominant male is nearby but a subordinate Peter Pan male is, females tend to stick closer together.

This is significant because orangutans are a solitary species. Fruiting trees are sparsely scattered in their habitat and don't come into season all at once so the habitat cannot support group foraging. Instead, rangs forage individually to be sure to get enough to eat and also leave enough to ripen for later. For females this artifact of habitat opens the door to being harassed by subordinate males. Dominant males rarely force copulations.

Obviously, one can draw some very interesting and provactive comparisons between humans and orangutans.


*** This pastel took a lot longer than the previous pastel I did on account of the time it took to put the tiny hairs on his face. I really like this one. I like how his eyes, nose, and lips turned out. I think he has a very typical orang expression.

My next pastel will be of a monkey without hair on its face. Candidates are: douc langur, snub-nosed langur, and bald uakari. I am leaning toward the snub-nosed langur because it has a very strange face - it's blue! Plus it is an incredibly rare species; I could not locate a single decent source to link to. The one I found contained plagiarized material.

Ravens: Masters of Deceit

Spiegel Online features well-written article about the intelligence of ravens; it's well-worth the read. It talks about the birds hanging on to the tails of boars to get pulled through the snow on their backs, playing dead next to a carcass to fool another raven into leaving the food alone, and other displays of intelligence. It also mentions a theory about how raven behavior might have driven the cooperative hunting seen among wolves. Very interesting. Though it's short on scientific findings, the shared anecdotes are entertaining. I also wish stories like these included references to the published science behind the story. I don't have time to go track it all down on my own!

Ravens look similar to crows but are much larger. You can easily see the difference in the photo above. Some people have raised crows, ravens, and starlings from birth to be pets. Mozart's starling became famous and possibly wrote one of his most famous pieces of music. Crows have been reputed to be able to learn to talk, but so have some dogs and cats whose owners swear they meow and moan things like "mama."

I've never met a talking crow but I did meet one once in the aviary here in town that vocalized every time Sleyed and I walked away and only when we walked away. It shut up when we reappeared. I think that qualifies as play. Crows are smart like ravens. Indeed, I've never heard of a dumb member of the corvid family. I've met the ravens of the Tower of London. They were aloof, but they meet a lot of people so it's got to be difficult to make an impression on them! Legend has it that if the ravens who live at the Tower of London ever leave, the monarchy of England will fall.

A new version of the Mind of the Raven, by Bernd Heinrich, will be published in June. I have the original on my shelf and recommend it to anyone who is interested in the minds of animals, particularly corvids.

Evidently some crows, magpies, jays, and ravens are kept captive in cages in the U.K. called "Larsen Traps" that use the captive corvid to attract another to keep the birds from interfering with "game birds" and song bird populations. The ACT website is interesting and highlights the hazards of human attemps to manage wildlife.

Lactose Intolerance

Over the weekend a good friend of mine visited for our college reunion. She's lactose intolerant and likes to enjoy ice cream and other dairy products so she brought lactase pills along with her so she could digest the milk sugar lactose. She was also told by her pediatrician the day after she returned home that she's got to fatten her one year old daughter up. I asked her how she's supposed to do that. Cheese! Makes sense, but she's worried her daughter might be lactose intolerant too. Being fully capable of digesting the stuff myself, the concept of lactose intolerance is not something I spend much time thinking about... until recently.

According to Steve Lewis, a professor of Darwinian medicine, mammals lose the ability to digest milk with age. This might "form a biological mechanism whereby the ties between mother and child are broken so that she can go on and have more offspring and the child can go and have offspring of its own." Symptoms of lactose intolerance include gas, bloating, abdominal cramps and diarrhea result. The NIH estimates that in the U.S. about 15% of people of European descent have it. Half of Latinos, 60-100% of Native Americans, 80% of African Americans, and 90% of Asian Americans are lactose intolerant. The ability to digest milk depends on how heavily a culture depended nutritionally on the milk of their herded animals.

What is really interesting to me from an evolutionary perspective is that lactose intolerance is something all humans should experience yet many don't. Relatively new research has discovered a genetic mutation that gave some adult humans the ability to digest lactose. This occurred sometime in the last 5,000-10,000 years and coincides with the origin of pastoralism in Europe.

This finding poses challenges to evolutionary theories about human behavioral adaptations (such as males' preference for mating with nubile women) that are thought to take hundreds of thousands of years longer to develop in a population. EPs can't go back in time to determine what kind of ecological conditions human ancestors lived in at the time we were evolving these adaptations (the so-called "environment of evolutionary adaptedness"), so most EPs infer what kind of behavioral adaptations would have been most adaptive for our ancestors by examining the ecological conditions of extant human hunter-gatherers. They assume the living conditions are essentially the same and that not enough time has passed for new adaptations to take hold, so if it would be adaptive for hunter-gatherers now it was probably adaptive in the past too. Obviously trouble arises when new evidence suggests that humans can evolve faster than expected. If a gene for making lactase well into adulthood can take hold in the last 10,000 years it is also possible that a gene for constructing hypothalamic-visual cortex connections in the brain that fire maximally for men viewing nubile young women could take hold that fast too. I seriously doubt that there was ever a time when the average man was turned on by the sight of a pre-pubescent or wrinkled old woman. It wouldn't make much sense for successful reproduction.

However, there are other adaptations that are more controversial and could conceivably be a product of relatively recent changes. The female orgasm, the desire for men to have more sex partners than women, sexual jealousy, monogamy, etc.

The discovery that lactose is newly digestible does NOT mean evolutionary psychology is a rotten paradigm, as some would have it (David Buller), but it does mean that care needs to be taken when hypothesizing adaptations that assume nothing has changed within the last 10,000 years.

As for my friend's daughter, she should be able to digest cheese just fine. Lactose intolerance doesn't set in until later in life and is a recessive trait, so if her dad can still digest lactose, she should be able to later in life too.

Cat Crap Cootie Changes Culture

A scientist working for the US Geological Survey and the CA university system has found out that a parasite commonly acquired by cleaning up after house cats can alter personality on a national level depending on country-wide exposure rates.

“The geographic variation in the latent prevalence of Toxoplasma gondii may explain a substantial proportion of human population differences we see in cultural aspects that relate to ego, money, material possessions, work and rules,” he says in the press release.

Apparently the parasite affects the personality trait of neuroticism. Neurotic people tend to be anxious and moody.

It's a stretch to go from there to "ego, money, material possessions, work, and rules" and the part about it explaining "a substantial portion" of cultural differences really overstates the findings I'd guess.

It all makes me wonder what the published study in the Aug 2, 2006 issue of the Proceedings of the Royal Society actually says.

My libraries only carry the electronic version up until 2000 and the print version won't arrive for several more weeks.... so I guess for now, we'll just have to take his word for it.

It is very interesting though! I love the studies that investigate how parasites manipulate their hosts so they can replicate even more efficiently. Parasite-host co-evolution is definitely one of my favorite evolutionary topics!

Here's an easier to digest version of the press release.

Explaining Evolution to the Masses

Francois asks over on his blog, in the face of such little acceptance of evolution among the general population in my country, how do I explain my research to non-scientists?

That's a good question - How do I explain my research?

I just come right out and say it, using non-jargon filled language. I explain it as if I am talking to my grandma or a 10 year old.

I study the nonverbal behaviors that humans have in common with primates. These include facial expressions, gesture, and patterns of touch. I want to know what we do, why we do it, and what it means when it happens.

Being someone who works in the field of evolutionary science (and specifically the much poopoo-ed version known as evolutionary psychology or SOCIOBIOLOGY) and being someone who is not shy about saying exactly what I think, I have experienced a variety of responses to my research.

From a lifelong family friend who is an evangelical Christian - how can you talk about animal cognition when they don't have souls? I guess I could see the point if psychology is taken as it literally means from its root PSYCHE meaning soul so that psychology is the study of the soul at least as it was originally conceived, but my field has changed a lot in the 130 years that the discipline has been around. Matter of faith have a very small place in psychology now. I think having the question of having a soul is totally irrelevant and arbitrary way to decide what should and should not be studied in psychology.

When I told a distant relative that I had just met that I study the behaviors that humans have in common with primates, she said "oh, ew" and didn't ask anymore questions of me the entire night. It was weird.

Others - scientists! - have expressed a lot of encouragement for my exploration of human-primate similarities.

But at least one person in my field, Kanazawa, has gone on the record (in a peer reviewed journal) to say that it is better to hide the similarities so as not to fuel discontent for our field among the uneducated masses.

I don't agree with him.

I have NEVER had a student attack evolution or the concept of applying it to human behavior. Perhaps that is a function of the types of colleges I have taught at.

Nevertheless, I am fully prepared to discuss evolution and human behavior with anyone, anywhere, anytime. I think it is my responsibility to keep doing what I'm doing.

Trouble is, the average American won't really read my stuff. We are self-selecting consumers. We like to consume what we like and know already.

"give us something familiar
something similar
to what we know already
that will keep us steady
steady
steady going nowhere"
~Fiona Apple

If you ask me, discomfort is the only way to g(r)o(w).

Those of us in evolutionary science ought to write columns for our local papers.

I wish I could do that but given that my husband works at the paper as an editor, I can't.

However, I do very much look forward to making my students (and any evangelical crusaders who knock on my door) uncomfortable.