[moh_maya]

Interesting as it is, and without taking away from the significance of their work, it is important to note that this was observed in rats. Not humans. Speaking as a biologist / geneticist, I think we should be very very cautious about extending observations in rodent social / sexual behaviour to primates, much less humans. Rats are, in general, remarkably aggressive compared to mice. Huge huge behavioural differences within just mice and rats!!

Here's an interesting example of the potential risks: http://www.smithsonianmag.com/smart-news/how-mouse-utopias-1...

"How 1960s Mouse Utopias Led to Grim Predictions for Future of Humanity"

[Edit: added link].

[tropo]

The mouse utopia experiment seems to apply disturbingly well to humans. Birth rate in urban parts of highly-developed nations (our utopia) has plunged way below the replacement rate. That's exactly what happened with the mice.

[moh_maya]

True. But not complete. Do we observe the same neglect of progeny, the same absence of "purpose" / directed activity in an equivalent human population (I.e., well off / socially successful individuals)?

As child rearing becomes more expensive, the number of children decreases. Do we assume, simply because whales (or elephants) have low birth rates, that their "societies" are living in an utopia?

A single common / overlapping data point is too insufficient, and therefore dangerous to infer that these are parallel processes. Which is exactly my point.

[Edit: refined language]

[jlgaddis]

I agree about not extending observations to where this hasn't been tested. The article noted, however, that this same behavior has been observed in monkeys so perhaps it's more prevalant than we think.

[moh_maya]

True. But, having looked briefly at the paper, I would hesitate to conclude that we are seeing the same biological / physiological effects manifesting themselves as similar behaviour as yet.

Convergent evolution- similar problems, similar solutions: but the mechanisms and nuances can be entirely different. And it is these nuances / small but significant differences that differentiate species.

Perhaps the common observation reflects the fact that, in any moderately complex animal "society" or group, certain outcomes are likely given similar circumstances.

However, not withstanding my general dismay at evolution being projected as a hierarchy with humans at the top (while evolution, if at all it is "acting" in a particular direction, is niche optimisation) there are far far too many subtle differences between humans and other primates.

I find it mildly distressing when scientists draw parallels with human society based on animal studies. I strongly feel that we still understand far too little of physiology and behaviour, even for rodents, to be able to draw such parallels. The risk is, we organise and plan actions that impact others according to a false model, which can have disturbing consequences.

To further muddy the waters, here is a paper that showed that fear conditioning in mice can be passed down epigentically to the progeny. It is a very good paper; but if you look at the citations, there is rigorous debate about the interpretation. Do read Brian's statement (the lead author) towards the end of the article. We know far too less right now to make any strong statements.

"Study finds that fear can travel quickly through generations of mice DNA"

https://www.washingtonpost.com/amphtml/national/health-scien...

And an open access review that discusses some of the current issues that are being debated:

http://rspb.royalsocietypublishing.org/content/281/1785/2014... "Can environmental conditions experienced in early life influence future generations?"

Edits: added links to the review