There's been no biological change in humans in 40,000 or 50,000 years. Everything we call culture and civilization we’ve built with the same body and brain. -- Stephen Jay Gould, "The Spice of Life", 2000
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That's such an extreme claim. It defies common sense. You'd have to proclaim that there was some event that _stopped_ evolution in humans, universally. How is that even possible? Especially 50k years ago. I'd be a little more forgiving if the claim was that evolution stopped in, say, 1999.
Rather a lot more things about human genomic history are known today compared to 2000.
Discoveries about being able to process lactose and when those genes evolved all were after 2000, for example.
Does it excuse Gould for making such bold claims? You have to decide I guess. That is a lot fuzzier.
I guess I would need to read more of what Gould wrote. For example, did he claim that evolution in other species also stopped?
I think the claim that humans stopped evolving is an uncharitable reading.
Another would be, 50k years is such a narrow window that evolution cannot be observed across it.
It's not an uncharitable reading if Gould stated his claim unequivocably.
Your alternative claim is just factually wrong. The population frequency of an allele under selection pressure can change within a few generations.
For example the HbS allele, that confers both sickle cell trait and malaria resistance, became less common among Africans transported as slaves to regions where malaria was not endemic.
You can observe evolution on much narrower timescales. People were following how covid was evolving after all. Evolution just means some changes to dna. Even identical twin children have some differences between them.
It's more of a function of selection pressure applied to genes per unit time based on some environmental factor, so you'd expect to observe less evolution in narrower timescales simply because it takes few decades for humans to pass on genes versus bacteria or viruses. In the same fashion, if some gene pool is locally optimal(?) against the environmental pressures, it may just stop evolving meaningfully. E.g, If male baldness were reversed easily with a pill or something, the environmental pressure to select those genes would decrease rapidly.
You can have evolution even within your own lifetime. Cancer progression, for example, is governed by selective pressures on the tumor.
Emphasis should be placed on "everything we call culture and civilization". There is a thought experiment that might help. Imagine we had a time machine, and no scruples, and we could go back and pluck babies from the past to experimentally raise them in modern American families. I'm pretty sure Gould would have argued that babies from 40k years ago would grow up to be behaviourally indistinguishable from modern humans.
Well, evaluating the nature of this thought experiment reveals what you actually believe about human evolution and development. I find it extremely hard to believe that someone from 40k years ago would be indistinguishable from humans today. Believing this requires you to imagine that there are no genetic selection pressures for things like intelligence, behavior, physical ability ... 40k years ago had Earth as an almost entirely different planet. Europe was frozen for most of the year, for example. There were no trees. Very, very hard to believe that people born back then could grow up to sit in front of a laptop today.
All we know basically is that their skeletons are undistinguishable from ours, with a brain the same size as ours (slightly later on average iirc) and what they left, tools and paintings, look just like what we can do as well (behavioural modernity, thought to arise some time between -100 000 and -40 000).
You can find it hard to believe, but I think most people in that field agree that humans from the last 40 000 years would grow up as modern humans without problems.
Sorry, you're claiming that people who lived in a desolate tundra 40k years ago are the same as you and me.
Can you be more specific? There's both a hardware and firmware element to this. Perhaps the hardware element is transferable.
The fondamental thing here is that humans 40k years ago could live in the toundra because we can live in the toundra today, and they had a similar behaviour to ours. So they made clothes and fires for the cold, and weapons for hunting the local fauna, just like we do. And they avoided actually desolate areas because they could not live without food.
That's why the colonisation of colder areas happened at about the time of behavioural modernity. Before that, humans where anatomically modern (mostly identical to us) but did not have the cultural equipment to deal with difficult environments.
>because we can live in the toundra today
No we can't. Have you been the tundra? You can't survive there on your own without technology. These people could.
Sounds like they just meant evolution takes longer than that?
To some degree it's true. We have all sorts of variable parameters that are probably different from back then (eg. Average height) but we still have the same body shape, etc
One should not read or pay much attention to anything Gould wrote or said. (http://cogweb.ucla.edu/Debate/CEP_Gould.html) The amount of damage Gould has done offsets any positives. It's not just even being wrong, indeed you can charitably read that quote as being almost correct (the phrase is "anatomically modern human"); the worst thing he's done is probably to mischaracterize the rest of the field as scientists believing things they don't (or haven't for many decades before he ever tried to address them).
Countering the nonsense prevalent in a lot of evolutionary psychology counts as a big positive in my book.
Despite being so famous, I feel like his ideas haven't aged well. His ideas were contentious yet embraced by popular science writers, and there's never been a reckoning.