I’m going out on a limb here but I don’t think the Tarahumara spend a lot of time creating and maintaining birdfeeders.
The European Blackcap
The European blackcap is a bird that migrated over the winter to Spain. Some, however, have headed to Britain instead of wintering in Iberia. In the past, they’d starve. Now they don’t. It seems that Brits relish birdfeeders, and some blackcaps relish them too.
Over the past 50 years, something remarkable has happened. A new species of blackcap is emerging, consisting of those whose parents (and parents’ parents) headed to Britain and had traits favorable for eating from feeders.
- The new blackcaps sport different plumage, beaks, and wings. They have rounder wings thanks to the shorter trip they now make, and longer narrower beaks–the better to eat from bird feeders, of course. These evolutionary changes took place in a mere 50 years.
The Impact of a Bird Feeder-Created Bird
So what’s the end impact of all of this–has man intruded on nature and disrupted yet another fragile ecosystem by sticking bird feeders all over the place for his own amusement? Or created a Frankenstein bird never meant for life in this world?
Thankfully, no–the scientists actually seem to think that the Brits have done the birds a favor: Dr. Schaeffer says, “[The birds have] found a better overwintering area that is closer to the breeding ground, where they can obtain food easily. And I also think its positive news for us, because it means not all the changes we produce are necessarily bad, and that some species have the potential to adapt quickly to the changes.” Well, that’s good to know–we humans are capable of doing a little good on this planet after all.
The Tarahumara, of course, don’t run barefoot. They wear slight sandals. But they’ve become the poster-children for the barefoot “movement.”
An argument from the barefoot crowd is that humans were born to run barefoot, that evolution favors barefoot running. But if there’s a lesson from the blackcap iit is that the way something is is not necessarily the best way. Call it the messiness-of-evolution. So something that might have been a liability — a long beak or short wings in the case of the blackcap say — can turn into an asset with the intervention of an outside element, a (perhaps) accidental artificial selection.
It’s been my oft-expressed view that wearing shoes allows those with varying efficient footstrikes to compete. For example, someone who is really fast when she heel strikes may not be so fast if forced to land on the forefoot (as barefoot running tends towards). With the intervention of a shoe, however, like the British birdfeeders, the fast way can be sustained.
In a transitional period, it may be that injuries may ensue at a higher rate than would otherwise be the case. That’s a different subject. But it appears that the example of the European blackcap connects some of the dots on the apparent contradiction between humans’ long-tradition of running barefoot and the predominance of form inconsistent with barefoot running in the world’s elite.
I know I keep going on on this, but this stuff rumbles around my head while I’m out running. Plus it gives me a chance to refer to the distinction between an African and European swallow. Knowing the difference can come in handy:
[Edited to add: The following is from what I originally put in the comments:
Re blackcaps, it’s the first step in becoming a new species. But I’m no biologist.
As to plausibility, remember that natural selection is not perfect. Good-enough is good-enough. And from “Catching Fire” it appears that those of our ancestors — not homo sapiens and I don’t recall what the species — whose feet were better adapted for running (as opposed to their ancestors tree-climbing) had an advantage and were more likely to survive and pass on this gene. But as the barefoot advocates note, the bare foot is in fact very well designed. Speed, however, was not paramount, as you can see in your Attenborough piece (sorry, I didn’t stick around for the kill itself but I did read McDougall’s description). They just had to stay close to their prey, and one guy going off the front was not going to do the group any good.
Perhaps if speed were the crucial thing (not sprint, Usain Bolt speed because they weren’t going to outrun their prey) the foot and the leg and the rest of the support system would have evolved differently. But the foot is good-enough for its purpose.
I should note that my comment really addresses the heelstrike v. forefoot strike issue and I am not a big fan of overly (however one defines it) running shoes. And I find fault with those who equate barefoot with minimalist since they are entirely different. My mantra: get the cheapest, least-engineered shoes you can afford (and recall that the evolution and Nike-sucks chapters were the only ones in “Born to Run” that I liked).
I don’t think we are the same of homo sapiens from 40,000 years back. Indeed, according to this article, humans are evolving faster than at any time before, but changes occur rather slowly.
- In a fascinating discovery that counters a common theory that human evolution has slowed to a crawl or even stopped in modern humans, a study examining data from an international genomics project describes the past 40,000 years as a time of supercharged evolutionary change, driven by exponential population growth and cultural shifts.
The findings may lead to a very broad rethinking of human evolution, especially in the view that modern culture has essentially relaxed the need for physical genetic changes in humans to improve survival.
A team led by University of Wisconsin-Madison anthropologist John Hawks estimated that positive selection just in the past 5,000 years alone -dating back to the Stone Age – has occurred at a rate roughly 100 times higher than any other period of human evolution. Many of the new genetic adjustments are occurring around changes in the human diet brought on by the advent of agriculture, and resistance to epidemic diseases that became major killers after the growth of human civilizations.
“In evolutionary terms, cultures that grow slowly are at a disadvantage, but the massive growth of human populations has led to far more genetic mutations,” says Hawks. “And every mutation that is advantageous to people has a chance of being selected and driven toward fixation. What we are catching is an exceptional time.”
While the correlation between population size and natural selection is nothing new – it was a core premise of Charles Darwin, Hawks says – the ability to bring quantifiable evidence to the table is a new and exciting outgrowth of the Human Genome Project.
As to bad eyesight — and for the record I am virtually blind without glasses/contact lens and would not have long survived (except, perhaps, via charity) were I not born in the past few hundred years (or were I a Tarahumara) — insofar as it is genetic in origin one would expect its carries to be less likely in the old days to reproduce and that the use of corrective lens would tend to cancel that tendency (notwithstanding the guys-don’t-make-passes-at-girls-who-wear-glasses notion) in which case the gene would probably become more common. But, again, I’m no biologist.
Take left-handed snails. They find it harder to mate, right-handed being predominant. But in some cases they have a greater survival rate because a predator snake has evolved to maximize its ability to eat right-handed snails and finds it more difficult to eat the left-handed variety, making the latter less likely to be eaten by the snake. So over time that gene would appear more frequently than it otherwise would have.]
[edited (again) to add: I just came across a photo of Kara Goucher at the Olympic Trials. A notorious heel-striker, you can see where her leg is just before it hits the ground. But it would appear that she is quickly moving so that she won’t be braking when she hits. I can’t post the photo, but here’s the link.]