Vox

Need More Proof That Evolution Is Real? Look No Further Than Your Own Body

DO try this at home.

SCIENCE AF STAFF
23 NOV 2017
 

Next time someone asks you for evidence that evolution is real, point them no further than your own body.

It might sound a little offensive, but your body is a museum, full of ancient relics that no one really needs anymore.

 

From your wisdom teeth to that weird way some of us can wiggle our ears, so much of how we ended up as humans reflects what our animal ancestors needed for survival, as the video by Vox below explains.

These strange remnants, that stuck around only because they're not 'costly' enough to have disappeared across many millennia, only make sense within the framework of evolution by natural selection. Have a look for yourself.

1. Your wrist

Here's one you can see for yourself right now: if you hold your arm out, and touch your thumb to your pinky, you'll probably see a raised tendon in the middle of your wrist. Right?

 

If you don't have that, lucky you - you're among the 10-15 percent of humans on Earth who were born without this prominent feature in one or both of their arms.

This tendon connects to the palmaris longus, a muscle that most of us have, but there seems to be no real reason for it being there.

Research has found that the presence of this muscle in our forearms does not give us any more discernible arm or grip strength than people born without the muscle.

In fact, it's so inconsequential, surgeons often remove it and use it for reconstructive or plastic surgery procedures elsewhere on the body.

So why did we end up with such a useless muscle?

Scientists have found that, while palmaris longus is present in many species of mammals today, it's most developed in those that use their forearms to move around - such as lemurs and monkeys.

2. Your ear muscles

Here's another one: have you figured out how to manipulate the three muscles around the base of your ear so you can wriggle it ever-so-slightly?

Good job - you're demonstrating how another evolutionary remnant has transitioned from an essential piece of equipment for our animal ancestors to a party trick no one cares about in humans.

 

Just like many nocturnal animals today - such as rabbits, gazelles, and cats - rely on the wide range of angles their ears can turn and face to better locate the origin of a sound, the creatures we've evolved from would have used the same trick millions of years ago.

And we haven't completely lost all of the 'equipment' they would have used.

As Vox points out, not only did humans retain three of the muscles involved in ear movement, studies have shown that these muscles still respond to sound. They don't respond strongly enough to make our ears move anymore, but they appear to give it their best shot.

3. Goosebumps

Feeling chilly right now? When we're cold, the tiny muscles that attach to our body hairs contract, pulling the hair upright and causing the surrounding skin to form a bump.

For our furry mammal relatives, this would have increased the amount of space for insulation and helped to keep them warm. For modern humans, with central heating and down jackets, it's less useful.

Even more impractical are the goosebumps you get when you're scared, or when you're deeply affected by music. These are also evolutionary leftovers.

 

That's because adrenaline is involved in the body's response to cold temperatures, and it's also part of the fight or flight response - goosebumps help furry animals appear larger when they're threatened.

And it's the same reason that particularly surprising or emotional turns in music can make some people's hair stand on end.

4. Tailbone

One of the most obvious evolutionary remnants is our tailbone - a bunch of fused vertebrae that serve as the anchor for some pelvic muscles, but not a whole lot else.

Of course, this is what's left of our ancestors' tails. In fact, at one point all of us had tails oursevles.

At around four weeks of gestation, human embryos have tails with 10 to 12 developing vertebrae. But in humans and other apes, the cells undergo programmed cell death soon after they appear.

Watch the video from Vox below to find out more, and see why that adorable thing babies do when they grasp whatever you put in front of their tiny fingers is also leftover from our ancestors.