THINK you have little in common with your prehistoric ancestors?
Think again.
According to a recent study by scientists in Sweden and Sheffield, evolution
in the 21st century is changing our genetic make-up and focusing less on our
physical appearance, meaning we are more similar to our ancestors than we
might think.
Here, JON AXWORTHY looks into the surprising evolutionary explanations
behind body parts and human habits.
Morning sickness
IT was not just being eaten that the original earth mothers had to fear during
pregnancy, but what they ate themselves. And their scavenging diet may have
blighted the first few months of pregnancy for modern-day mums too.
A study from the University of Wroclaw in Poland has found women in their
first trimester are hypersensitive because it is the body’s way of
preventing infection.
This is an evolutionary hangover because there was no such thing as prenatal
diets in prehistoric times and mums could not be choosy about what they ate.
So the body defended itself by expelling anything that was deemed harmful,
particularly in the first twelve weeks when the immune system is most
suppressed.
Pruney fingers
STAY in the bath too long and you’ll experience this bizarre phenomenon.
It was assumed it was just the skin swelling underwater but tests at the
University of Newcastle found wet objects are easier to grip once the ridges
in our skin have formed.
Dr Tom Smulders, director of the Centre for Behaviour and Evolution, says:
“Wrinkled fingers may have evolved as rain treads. Either in our primate
ancestors who had to move through wet environments and needed grip, or our
immediate ancestors for foraging in water to give an advantage when
collecting shellfish.”
Or, in our case, a slippery bar of soap.
Goosebumps
EVER wonder why your skin gets bumpy when you’re cold or in a heightened state
of emotion?
If you were a little bit furrier, you would know that this physical trait
comes from your more hairy heritage.
Attached to all the hair follicles on your body is a minute muscle, called the
piloerector, which can suddenly contract to raise the hair.
Animals still use these muscles to raise their thick hair up — either to make
themselves look bigger when threatened or to trap air in their coat when
cold.
Oddly enough, humans still have the neural pathways for this effect but, over
the years, they have lost the thick hair that goes with it.
Ear wiggling
CHARLES DARWIN first identified “vestigial traits” that were once crucial to
survival but, over time, have become surplus to requirements.
No doubt he was wiggling his ears when he came up with the idea because this
is one of the traits.
Jerry Coyne, evolutionary biologist at the University of Chicago, says: “In
our ancestors, moving ears to localise sounds was advantageous.
“It’s a remnant of a trait that was useful in some mammalian ancestors and
still is in some living mammals, but is no longer of any use in humans.
“Primates depend more on vision, so selection has been relaxed on ear movement
in our lineage.”
Map reading
IT’S a classic male-female argument when totally lost — she wants to ask the
way but he is sure he knows where he is.
Well, thanks to a University of Utah study, guys can blame their certainty at
not being lost on their ancestors.
Researchers studied Namibian walking tribes who face similar challenges of
distance and navigation.
Men who scored well on spatial skill tests — the ability to mentally
manipulate objects, such as tell where they are on a map — travelled
further. And they performed better on average than women.
Scientists found the ability to navigate long distances was invaluable in
ancient hunter-gatherer tribes and has been retained in the brain’s
circuitry.
Farting
OUR over-reaction to someone breaking wind is the brain’s attempt to protect
us from bacterial disease.
Dr Simon Park, at the University of Surrey, says: “A fart will emit bacteria
but in a healthy individual these are likely to be harmless members of the
gut microbiome.”
Gas was an issue for our ancestors, who didn’t know who was healthy and who
wasn’t. Thankfully, we now have underwear so don’t have to worry about
contact with pathogenic particles but we still react violently to the smell.
High noise
WHETHER it’s a non-stop car alarm or the chorus of the latest Katy Perry
single, those grating sounds that leave you wincing have been linked to
similar reactions in primates to alarm calls.
Studies from Northwestern University, in the US state of Illinois, found the
noise of a metal object being scraped across a blackboard was sonically
similar to the warning calls of macaque monkeys and that it caused us
physical pain in our ears.
Even though the threat of being gobbled up by something has long gone for us,
we still have a sensitivity to the sound. The theory being that, a long time
ago, those not sensitive to the sound became dinner, leaving behind those
who were alert to pass on their genes.
Boozing
THERE is even an evolutionary explanation as to why we’re drawn to a glass of
wine or that after-work pint.
Researchers at the University of California say alcohol has been associated
with nutritional rewards ever since primates began to eat fruit.
The smell of alcohol fermentation from fruit in the warm, moist tropical
climates we evolved from led our ancestors to the fruit in the first place.
The brain then developed psycho-active rewards every time the fruit alcohols
were eaten to ensure the animals kept coming back.
And it’s these pleasurable feelings that are still with us today — and what
keeps us propping up bars worldwide.
Junk food cravings
THANKS to our local takeaway joints, we no longer have to hunt for
high-calorie foods, unlike the original bipeds that had a much tougher time
finding a meal.
Whenever they found a tasty food source, their brains released feel-good
chemicals as a survival mechanism to keep them coming back for more.
Leigh Gibson, a reader in biopsychology at the University of Roehampton, says:
“Our brains have evolved as energy-hungry organs and they are holding the
reins of our behaviour. This is why we crave high-calorie junk food.”
Wisdom teeth
BAD news for future dentists — in 10,000 years, no one will need their wisdom
teeth taken out. A quarter of the world’s population lack at least one of
the third molars because we just don’t need them any more.
Anthropologist Prof Alan Mann says: “As our brains got bigger, so the shape of
our skulls changed. The trait may die out completely one day because people
with aching jaws might be less likely to have children as the pain has put
them off sex.”
So the next time you hear someone complain they’ve got to have their wisdom
teeth out, you can say that at least they’ve guaranteed their place in
evolution for another ten millennia.
Your third eyelid
HAVE a look in the mirror. In the inner corner of each eye is a small, fleshy
bump — that’s your third eyelid, or at least, what remains of it after a few
million years.
Paul Miller, a clinical professor of comparative ophthalmology, says: “It is
pronounced in dogs and cats who use it to protect the eye.
“However, it may have lost its advantage for us as we no longer have to
capture food or forage through vegetation with our mouths.” Now there’s no
gain in having the covering, so it has retreated to nothing.
