Make and fix and mend;
But now it’s at an end;
The sentiment conveyed in this song is a common one. Evolution, according to most, no longer affects us. No doubt you’ve read something talking about how humanity has removed itself from the natural world to such an extent that we are no longer evolving.
Such statements are typically incorporated into some kind of rant about the evils of humans. About how we’ve divorced ourselves from what is good and natural so much that not even evolution can touch us now.
On the surface this idea seems to make sense: over the past few thousand years we’ve been effortlessly working to not die malnourished on some ratty bit of grassland. A noble goal, in my opinion.
This has turned humans into experts at niche construction (the sciency word for organisms which create their own environment) and if we’re building our own niches then why do we have to adapt? We can just keep things ticking comfortably along the way we like them.
And this does seem to be the case. A disease tries to kill us, we set doctors on it. We feel peckish, we head down to the local supermarket. A lion runs at us, we shoot it. We get cold, we were an undershirt…the list goes on. Every time evolution tries to point out we have no right having 7 billion members of our species sprawled across the globe, we punch it in the metaphorical face.
We work to maintain a stasis whereby we remain alive and happy, regardless of the environment.
However, whilst ostensibly valid this logic runs into a pretty critical flaw: we don’t keep things the same. Humans now occupy more extreme territories than they have at any point in the past, from the Antarctic to Space, in larger groups than at any point in the past, with a different diet to at any point in the past.
This is the premise of inceptive niche construction and is an aspect of our technological advancement that is frequently overlooked. Basically, it is pointing out that changing our habitat can create new environments or allow us to inhabit previously unaccessible ones.
Before we developed sufficiently advanced technology we would’ve been inhabiting a rather different environment than we do today. Even after removing various selection pressures – suh as diseases and lions, as previously mentioned – we’re still living in a drastically different environment to the one we would typically be in.
But of course we are also generalists, able to survive quite well in a large variety of environments. Perhaps our new environment, despite being different to the African Savannah our species grew up in, is still within our tolerance and we do not have to evolve after all.
Thus the question becomes whether the selection pressure we create by using out technology to create/survive in new environment are sufficient to drive evolution forwards.
And the answer to that question seems to be yes! There are examples where recent inceptive niche construction has brought about evolution in Homo sapiens very recently.
- Domesticating cattle and consuming their milk has prompted lactose tolerance to persist into adulthood within the last 8,000 years.
- In areas of the world technology (amongst other factors) has helped eliminate malaria, sickle cell disease has also disappeared.
- The age of menopause is increasing in many populations, possibly due to niche construction improving the health of the elderly.
All in all, it would seem around 13% of our genome is currently under selection pressures*. So, whilst we may be living in a seemingly artifical environment we have yet to escape the natural process of evolution.
Make and fix and mend;
It’s not yet at an end;
|Laland, K., Odling-Smee, J., & Feldman, M. (2000). Niche construction, biological evolution, and cultural change Behavioral and Brain Sciences, 23 (1), 131-146 DOI: 10.1017/S0140525X00002417|
*That does include “purifying selection” where evolution removes deliterious mutations. But ultimatley that is still evolution in action, even if it is not moving us forwards.