Are human beings still evolving in response to any recognizable factors?


#61

Germs often evolve in one species, and then find that they can infect other species. Modern examples include SIV/HIV and Ebola. I think it is usually a question of when, not if, this will occur again.


#62

Yes, and one factor in emerging viruses is that we are destroying habitat and coming into contact with animals that were previously more isolated.


(Jay Johnson) #63

We used to think war was uniquely human, but here’s a passage from Demonic Males: Apes and the Origins of Human Violence

"The social world of chimpanzees is a set of individuals who share a communal range; males live forever in the groups where they are born, while females move to neighboring groups at adolescence; and the range is defended, and sometimes extended with aggressive and potentially lethal violence, by groups of males related in a genetically patrilineal kin group.

“What makes this social world so extraordinary is comparison. Very few animals live in patrilineal, male-bonded communities wherein females routinely reduce the risks of inbreeding by moving to neighboring groups to mate. And only two animal species are known to do so with a system of intense, male-initiated territorial aggression, including lethal raiding into neighboring communities in search of vulnerable enemies to attack and kill. Out of four thousand mammals and ten million or more other animal species, this suite of behaviors is known only among chimpanzees and humans.”


#64

That looks like a very interesting book. I had to search for mentions of bonobos, and I wasn’t left disappointed:

"What marks have those ancient evolutionary forces forged onto our twentieth-century psyches? And what do they say about our hopes and fears for the future?

These problems prowl at the heart of this book, and they are gripping enough. But they are made all the more curious by one strange, wonderful discovery of the last two decades. We have seen that chimpanzees and humans share, with each other but with no other species, a uniquely violent pattern of lethal inter-group aggression visited by males on neighboring communities, and we know that one possible explanation is inertia. As we will show in later chapters, the same applies to other patterns of violence, such as rape and battering. But one final act destroys the theory that chimpanzees and humans share this appalling legacy merely by viture of having shared a common ancestor who once behaved in the same unpleasant way. We know that inertia fails to explain similarities because chimpanzees have a sister species: the bonobo, or pygmy chimpanzee. Chimpanzees and bonobos both evolved from the same ancestor that gave rise to humans, and yet the bonobo is one of the most peaceful, unaggressive species of mammals living on the earth today." [transcription errors are mine]


(Mark D.) #65

Figures it would have come from distant cousin Cheetah’s side.


#66

And Jane Goodall was the one who discovered that Chimps go to war.

The bonobo ladies run things! And every bonobo has sex with everybody else! Primatologist Frans de Waal calls them the hipppies of the animal world. If St. Paul had heard about them he would have had a fit. They make the Corinthians seem tame by comparison.


(Jay Johnson) #67

The author was working for Goodall when he made the discovery, actually.

The Amazon description of the book includes this provocative statement: “Drawing on the latest discoveries about human evolution and about our closest living relatives, the great apes, the book unfolds a compelling argument that the secrets of a peaceful society may well be, first, a sharing of power between males and females, and second, a high level and variety of sexual activity, both homosexual and heterosexual.”

I don’t know about the first, but the U.S. seems to be following his advice on the second point, and I don’t see a whole lot of peace breakin’ out.


(Jay Johnson) #68

The problem with the “hunting hypothesis” is that all predators are hunters, yet all hunters did not evolve those traits you mention. One of the most influential theories of how humans evolved to have those capabilities is Sarah Hrdy’s Mothers and Others. In her view, the key change was a change in child-rearing strategy – from mothers alone being responsible for the care and feeding of infants to “mothers + others,” meaning an extended family of female caregivers, accompanied by sexual division of labor. Those two things alone allowed human females to reproduce twice as fast as the great apes. But, more importantly, according to Hrdy, this change in child-rearing strategy provided the framework for things like intention-reading, theory of mind, and empathy to arise.

Returning to the OP, which asked whether humans are still evolving, Hrdy observed modern daycare and foster care systems and concluded:

"For hundreds of thousands of years, an interest in mind reading and in sharing mental and emotional states has provided the raw material for the evolution of our unusually prosocial natures. But if the empathic capacities of infants find expression only under certain rearing conditions, and if natural selection can only act on genetic traits that are actually expressed in the phenotype, perhaps we need to be asking how even the most useful innate predispositions can persist if their development is not encouraged?

“After all, ‘the’ human species is no more static than other species are. If our environment changes (or, more pertinent in the human case, as we transform our environment), we change with it. So why wouldn’t novel modes of childrearing continue to shape not just child development but human nature? To anyone who wonders whether the processes postulated in this book could ever be reversible, I would say that there is no reason why not. Just because humans have become ‘advanced’ enough to vaccinate their young, write histories, and speculate about our origins, this does not mean that evolutionary processes have ceased to operate.”

Hrdy wonders what happens to a society in which “regarding motives like empathy and social emotions like shame” are not selected for, but rather the contrary. She suggests that current Western societies might be of this type: individualist, consumption-oriented, and alienated. In other words, our cultural evolution is moving farther and farther away from the conditions that gave rise to our big brains and prosocial traits such as empathy, yet modern technology and medicine mean that “an ever-increasing proportion of the species fails to encounter those conditions, but nevertheless survives to reproduce."

Hrdy spells out the possible consequences for human evolution: “If empathy and understanding develop under particular rearing conditions, and if an ever-increasing proportion of the species fails to encounter those conditions but nevertheless survives to reproduce, it won’t matter how valuable the underpinnings for collaboration were in the past. Compassion and the quest for emotional connection will fade away as surely as sight in cave-dwelling fish.

(That was for you, @BradKramer. :wink:)


#69

Is he claiming that he made the discovery?


(Jay Johnson) #70

I would have to go back and look, but if memory serves, he was Goodall’s research assistant and first documented the behavior. Goodall, of course, would be the one to write it all up and draw any conclusions, since she was in charge. Take all that with a small grain of salt, though. My memory isn’t what it used to be.


(Bill Wald) #71

It depends upon how one defines “evolvution.”

If it implies that the critters most adapted to a changing environment have the best chance to pass their DNA to the next generation, then every generation since penicillin was discovered have become weaker.

If another “Carrington Event” occurred, all modern electronic devices would die and so would half the population of the US.

If evolution implies that one sub-species out-populates another sub-species, then the US “middle class” are in big trouble.

There is no historical data that humans are more moral or smarter than we were 6,000 years ago, only more “technical” Technology builds on existing technology.

There is no evidence that human nature has changed in the last 10,000 years.


(Lynn Munter) #72

Intelligence in the animal kingdom correlates both with animals that live in social groups, and with predatory and omnivorous behavior as opposed to herbivory. Animals that hunt in groups are particularly prone to developing a lot of brainpower. Wolves, dolphins/orcas, and us.

The type of thinking associated with tracking specifically, as would be necessary in a long-distance chase as opposed to an ambush or sprinting like a cheetah, is particularly abstract, especially considering our olfactory sense is fairly atrophied so we would have to rely primarily on visual cues and prior knowledge.

Group child-rearing is of course a major part of strongly social animals, but there are lots of examples of it out there that fall short of human intelligence as well. But I do think the two areas are not as unrelated as they might seem at first.


#73

It’s possible that he’s trying to take credit for her work, but I will check it out.


#74

She’s right that humans have the ability to dissipate heat by sweating profusely when running extremely long distances when hunting. (Horses also sweat all over. I remember riding bareback and my jeans would be wet with sweat!) But I don’t think she’s right about the other stuff. (I was somewhat jealous when I saw what long-distance hunters can do. I can’t even catch my dogs when they run off.)


#75

Doesn’t require any more abstract thinking than flint knapping, attaching a blade to a shaft, organizing a hunt, painting cave walls, making beads, carving figurines, or any other wonderful thing our ancient ancestors did.


#76

Parrots don’t hunt but they possess great intelligence. And their brains are the size of a walnut. Read “Alex and Me” by Irene Pepperberg. It wasn’t easy for her to even get grants, let alone respectability for her work.

Crows are another very brainy bird.


(Lynn Munter) #77

Parrots are enormously social, and crows are a primary reason I included omnivores. :smile: A lot of birds are surprisingly smart.


#78

I wouldn’t say that omnivory in the animal world is correlated with intelligence.


(Lynn Munter) #79

There can be a wide variety, depending on exactly what kind of ecological niche it is and what kind of animal. But all I really have to say is…

RACCOONS!


(Lynn Munter) #80

Yes, but it predates most of them on the timeline, and is an answer to how our ancestors could have gotten the calories needed to increase their brainpower before there’s any evidence of weapon-making.

The people saying they could have been ambush hunters—really? What about our bodies seems suitable for leaping out of a tree and wrestling a healthy wildebeest into submission? A chimpanzee would probably be better at it than us, or at least get less hurt. I don’t see it.