How is modern life impacting human evolution?

Factual Questions
21

They’re not non-survival genes. They don’t reduce survival in the current actual conditions.

What is and isn’t a survival trait depends entirely on what the conditions are.

What’s a survival trait, under current conditions, is the ability to stay alive and reproduce while living with a very large number of other members of the same species; which, considering how good we are at weaponry, means managing not to get into too many fights with other people. We may be getting better at that; though we may not be doing it fast enough.

I suspect our intelligence has developed in large part to serve out ability to manage social situations. Hunter-gatherers need to do this. Farmers need to do this. Fishers need to do this. Humans all over the world need to do this. There are no human groups that aren’t going to find intelligence a survival trait.

Also – agreeing with others: you need to know different things to hunt than you need to know to plant food (plus which lots of people did, and do, both.)

I do, actually.

Humans tend to want to think that everything else is stupid.

And humans who rely on hunting do much of it in social groups, and as a learned activity. – for that matter, hunting in cats is partly a learned activity. ‘Chase the little moving thing’ is inherent; ‘stalk it and then catch it in a fashion that won’t get you hurt yourself, and eat it afterwards’ is learned.

I grant that hunting in spiders is probably pretty much built in; but it’s marvellous, all the same.

Humans also tend to want to think that people unlike themselves are stupid.

Rural farmers and city slickers know different things. One group doesn’t know more things than the other.

22

Does it? Back that statement up. A chimp can hunt, even cooperatively. Don’t see them growing any food, though.

…and farming doesn’t?

Note also that most “hunting” societies were not exclusively hunters, they also were gatherers. So focusing on the 10% of time when they maybe had to be as smart as a chimp hunting a duiker, versus the 90% when they had to be smart enough to sneak up on some berries, seems lopsided.

Quicker thinking =/= more intelligent. Even allowing that hunting requires quicker thinking than e.g reacting to floods, or pest infestations, or any of the other myriad things farmers have to deal with daily, which I don’t concede.

23

Are you referring to microevolution or macroevolution?

From a purely genetic perspective, there’s no reason why wealthier people would have more children than poorer people. However, wealthier people should have had a lower child mortality rate (fewer starving children). Modern first world society enables almost anyone to raise children, even extremely poor parents.

While humans can travel, in most places races stay “separate”. I’m not referring to racism, but chances are you are going to marry someone you know in-person, so someone close by. In fact, I doubt we will see many shifts except in large multicultural societies with lots of immigrants.

Modern medicine has impacted evolution dramatically. People can live a long time with poor vision (glasses, contact lenses, etc), without functioning immune systems, organs that stopped functioning (organ transplants), hemophilia, inability to walk, and so forth. Many of these cases are genetic: for instance, I have a genetic vision disorder, and if I live prior to the development of glasses, I would have had to live at home and would never have been considered for a mate.

24

You’re just comparing one simple component of activity A (an individual dropping a seed on the ground) to multiple components of Task B (weapons crafting/training, language, teaching, coordinating, planning). Of course 90% of task B takes more collective intelligence than 2% of Task A; but what’s that prove? And why would you overlook or discount the planting process being already been mapped out for generations… didn’t that literally take generations worth of study and practice?

A simple example is Christopher McCandless (the guy the movie “Into the Wild” was based on) in real life with little to no experience managed to successfully hunt lots of animals with a little 22 rifle… including a moose of all things. That didn’t require coordination; in fact he did it in secret with no license or help (he was poaching). But part of what may have helped do him in may have been eating the wrong plant. It takes a bit of knowledge to know what’s edible or not when farming/foraging.

25

Hunting versus agriculture is an odd comparison. My cat is a very efficient hunter. Much too good really. But there is zero chance he will ever grow something for himself to eat.

Humans evolved a very specific trait to become successful hunters. Endurance. We can wear down almost any animal to the point where all we need do is walk up to them and kill them. We however are terribly equipped for hunting in many other ways. Poor sense of smell perhaps the most obvious.

Agriculture requires an ability to plan for the long term. And an ability to reason about the nature of plants, cause and effect. Understanding the life cycle of plants and so on. The ability to plan beyond the moment is something that sets us apart. Language and the ability to learn from others is another thing that enables agriculture. The ability to develop a cultural knowledge of how agriculture works, and to improve upon what has gone before.

26

[quote=“Francis_Vaughan, post:25, topic:955903”]Agriculture requires an ability to plan for the long term. And an ability to reason about the nature of plants, cause and effect. Understanding the life cycle of plants and so on.
[/quote]

An ability to reason about the nature of animals, cause and effect; understanding the life cycle of animals and so on; will certainly improve hunting skills. An animal that humans are running down is likely to be out of sight most of the time during the beginning of such a hunt; plus which, it’s necessary to find it in the first place; to know whether and where it might have decide to ambush the hunter instead; what it can and can’t climb – considerably etcetera. (I suspect that many animal hunters learn a lot of this stuff too.)

Even planning for the long term is likely to come into it: many animals travel to different locations at different times of year. Planning to be in the right place when the herd comes through requires long term planning.

As you note: humans, aside from our ability to keep travelling for long stretches of time, are pretty terribly equipped to be hunters. We need to make up for that by other techniques, which require intelligence and learning.

So, of course, does farming. This whole it-takes-more-brains-to-do-one-or-the-other discussion is I think a misapprehension. Different fields of knowledge are involved; but they all, as done by humans, require brains.

I suspect that what really pushed us to bigger brains, though, was telling each other stories: an activity engaged in by just about everybody human.

27

The Marching Morons and Idiocracy are a little too simplistic takes, I think, but there’s a certain grain of truth there.

Population growth is in the process of collapsing. It’s going to cause serious demographic problems in some places already. I think it’ll affect even developing areas soon enough.

Why is this happening? Hard to say for sure, but it’s clearly not because it’s expensive to just produce children. It is, among other things, expensive to produce children in ways that prospective parents might want–having a large enough house to support them, sending them to college, hiring a nanny, and so on. But just having a kid with a reasonable chance of making it to reproductive age? Cheap. The cost problem is with high standards, not the bare minimum expense.

And then, many people just don’t want kids, or have some personal reasons for not wanting to bring a child into the world. The list is really endless here.

So who is left? Well, the stupid are possibly one group–people that can’t figure out how to work birth control, say. There are religious folk who consider it a duty to reproduce. And there are people who just plain have a strong drive to have children–they want kids, at any expense. Another factor is the desired family size–people with a desire for large families will propagate their genes more.

I’m sure there are a whole host of genes related to these factors. People who like kids will have kids that like to have kids. And so will others, and then the genes will be more prevalent in the pool and thus be even more likely to reinforce each other.

Thus I think the population crunch problem will be somewhat self-correcting. People without any type of “I must have kids” genes will be less likely to propagate. The remaining pool will pass on those genes, and be more likely to mate with others that have them as well. It remains to be seen whether the most powerful force is stupidity, religion, a generic drive, or something else. It also remains to be seen how quickly this will happen–at what point it will catch up with the societal factors that are causing the decline in the first place.

28

Yeah the Homo genus’ brains ballooned in size crazy fast. So I tend towards hypotheses that it was being smart compared to other humans – in socializing, cooperating and competing – that became the critical selection factor, because that would have a runaway effect.
No so much about solving any particular problem in our environment, but it’s just IMHO.

29

As was discussed in a much earlier thread - I observed that something happened about 70,000 years ago, and the humans from that event burst out into Asia then the world, replacing previous iterations of homo. Was it actual language? Conceptual or abstract thought? Whatever it was, we won.

We can debate it and not convince each other, but I still think that hunting takes more intelligence. A hunter must personally react to the circumstances they encounter in short order, recognize animal behaviour, etc. .A farmer can follow the rote steps that society has figured out for him. Perhaps my comments about farmers not needing as many skills would more apply in the context of civilizations, where the same sort of factors apply that we are discussing for modern life. Originally, we may have evolved harrying the larger animals to exhaustion, but there are multiple different modes of hunting today which can involve stealth, trickery, patience, etc. solo or in groups. Hunting also needs to be a large group effort in some circumstances, with cooperation and sharing proceeds. Farmers often are reliant instead on their own family work, rather than combining the efforts of the whole society. Yes, both have assorted tasks such as making the tools of their trades that challenge their intellect. Also, hunters tended to be smaller groups responsible for their own defense, whereas settled farmers in civilization rely on a higher power for protection (since the marauding enemy bands will also be much bigger)

Yes. The point is, we are changing the distribution of genetic attributes to the point where humans overall are adapting to fit more and more into a specific niche - “Advanced technology society”. Fewer people are going to be able to physically survive and reproduce outside that niche, even with the process that made us the dominant species, i.e. instruction and learning. If advanced technology society is not going away then yes, “who cares?”. But if a disaster, such as a hurricane or ice storm destroying the power grid or the entire city for weeks, or major floods, is a risk to survival, then those persons are “maladapted”. Ditto for weakened immune systems reliant on regular access to drugs; or needing supplies like insulin; or needing a wheelchair, or someone to help you get up and get dressed in the morning. etc. etc. The chaos that engulfed large areas of eastern Europe 1941-45 is the sort of thing that would break that narrow survival niche.

30

I don’t always keep up on everything paleoanthropologic, but I thought the current thinking had moved the out-of-Africa date back to 90-100,000 years ago.

My understanding is that that mode of hunting has never been the most common form, even with the earliest hunters. It’s too exhausting for the hunter and there’s other, more efficient, ways.

31

Ooof, those are some perilous terms. I mean, yes, they’re legit scientific terms, but they’ve also been ill-used by YEC types , so I wouldn’t introduce them in a discussion about an evolution topic without making quite clear what I mean by them.

32

Brains, and, later, improved tools, is what made us successful hunters.

The persistence hunter hypothesis is still just that, a hypothesis, and there are criticisms of both the hypothesis and the research that underpins it. For one thing, a lot of the fieldwork used to support it is around the Kalahari HGs, who a) don’t live in the same environment as early hominids, b) make extensive use of poison, which isn’t mentioned in the PopSci articles about endurance hunting, c) don’t rely just on their bodies’ endurance but carry stores of water and food and d) more often use tracking than just endurance running. Sure, they’re good endurance runners, but their hunting stategies don’t match the actual proposed persistence hunting “wear them down” model. More like “just follow them while they die from arrow poison”.

It’s this fundamental error of looking at modern HGs and just assuming they’re not vastly different from our hominid ancestors, when they’ve had just as much evolutionary distance from them as a New York stockbroker…

33

You equate spiders with humans? The idea that humans don’t need to learn to hunt, or be taught to do it, is laughable in the extreme. There are few things in the pre-modern world that were as complex and needed as much training, from toddlery to adulthood, as hunting.

We don’t use our claws and innate jumping ability to feed ourselves. We have to invent and craft all kinds of never-before-seen weapons, or simple machines, and then task our memory, deduction and tactical thinking to find game and get close enough to it, for primitive weapons to have a chance, and that on a regular basis. The fact that early people, in vastly different environments, could live off that, is a marvel.

34

Does it matter whether hunting or agriculture requires more smarts? How did we get on this tangent?

35

The logic is that modern society has sidestepped evolutionary pressures, including the ones that weed out traits detrimental to survival (more precisely, “survival in the wild” or “survival without the benefits of modern society”). The corollary is that this sort of pressure has been happening since humans abandoned hunting for settled agricultural life. At the very least, nomadic hunting as a means of feeding oneself requires some basic traits - passable eyesight, ability to walk, etc. that are less important for agricultural life. The area of debate is how selective for intelligence is hunting vs. agriculture. (Because animals are smarter than plants at avoiing getting caught) Add in modern medicine and numerous other traits are now not being “bred out” any more.

36

A lot longer than that, most likely. Look at our undersized teeth and jaws – they’re probably the result of our developing cooking and weapons; both of which predated modern humans, never mind agriculture.

Passable eyesight and the ability to walk are both essential for agricultural life.

If what you mean is that people settled in one place found it easier to keep alive a small percentage of members who were lacking passable eyesight or the ability to walk, that’s true. However, that behavior and ability also long predates agriculture – Neanderthals kept such people alive.

37

Yes, the just-so-story about human evolution, along with us running down big game was…

Humans originally began coming down out of the trees to scavenge the expanding savannah. Our omnivorous tendencies led us to scavenge the leftover carcasses of big predators. Using sticks and stones to drive off competing scavengers taught us about weapons. Upright posture and bipedal walk evolved originally as a positive adaptation to allow carrying more food back to the safety of the trees. Because we learned to use fire about then, we went from scavenging old meat that had already begun breaking down, to cooking meat - so never adapted to a diet of mainly raw meat. Possibly finding carcasses in the aftermath of grassfires helped demonstrate the value of cooking. meanwhile, the large helpings of protein in meat helped fuel our bigger brains, which consume 20%-30% of our total nutritional intake and so needed to be fed copiously.

But then, that’s evolution. (The simplistic version) The ones who could walk upright and carry stuff longer and further survived better; the ones who could run endurance marathons survived. The ones smart enough to cooperate and plan out hunts survived.

The thing with endurance is not “running down” big game. Grass is very low in nutritional value. Grazers need to eat a lot of it to survive. If a hunting party keeps harassing a herd so they have to keep moving, can’t stop and eat or drink for any length of time, eventually the animals are hungry and exhausted, especially, if the harasser has the smarts to carry their rations with them or do it in relays. (And the planning to herd their prey away from watering holes)

(One comparison I read said that the mountain gorillas and chimps will spend up to 11 hours a day chewing on their much lower nutrition herbivorous shoots and berries, while humans eat large gobs of cooked meat with fat, high in calories and nutrition. Cooking also minimizes the amount of chewing required.)

there’s no doubt that group action protects the less capable - we see this in herd aggression against predators to protect the young unable to fend for themselves. The question is whether society takes this too far, to the detriment of the gene pool. (And if so, what should we do about it, if anything?)

But to get back to the OP, if evolution is gene selection based on environmental factors, then the survival in advanced societies of less “precise” genes that would in other environments more likely result in failure to survive and reproduce - is in itself a form of evolution that is changing the gene pool.

38

I’d guess that the most recent change that’s had an effect is the availability of travel technology. It allows us to mix genes across and between continents.

39

I think in the near term (next several generations), we’ll see fewer phenotypically white people. As mentioned upthread, rich people are having fewer kids, and white people are overrepresented among the rich. Plus, the genes for light skin, hair, and eyes tend to be recessive or co-dominant, and as a society we tend to round mixed people up to people of color. As the stigma against interracial marriage fades and more white people partner with nonwhite people, we’ll see even fewer babies born who would meet our current definition of “white.” This may be good for our survival. As we burn off the ozone layer, our kids will probably need more melanin than what most humans have needed for the last several generations.

40

The ozone layer is actually starting to recover, thanks to banning various problem substances.