Murphy

being something of a cynic, i would disagree and say that i think the next main spur to evolutionary change in humanity will be the fall of civilisation, at least to the point where we lack the medical technology necessary to keep maladapted people reproducing.

Elvithriel

The next step in human evolution is human technology itself. Since evolution is not intellegent there is a limit as what it can do.

Standard evolution for human is effective at and end since natural selection isn't what it used to be. The next step is to use the technology to intelligently design ourselves apart from evolution.

Choy Lee Mu

The problem here is that we have no flippin' clue what would be a good survival trait to genetically engineer into ourselves.

Monkeying around with our genes (forgive the allusion) to make ourselves "superhuman" is dangerous to the species because we don't have any idea what we're doing yet. Who's to say that a "superhuman" (as we envision them right now), are the best possible chance for species-level survival?

Maybe the horseshoe crab is the pinnacle of evolution on this planet and we're a mere abberation. Let's face the cold, hard facts. On a evolutionary timescale measured in billions of years, the human race, at it's current level of self-awareness and intelligence, is nothing more than a very small blip on the radar. We need millions of years to determine if a self-aware, intelligent primate species can survive.

We may not be.

Peez

I can see why you might think that, but it is not necessarily true. Let us ignore genetic drift for the time being (it is likely to be very weak in a population of over six billion). What is required for natural selection is variance in fitness, essentially variability in reproductive rate among individuals in a population. Of course one must survive at least to sexual maturity in order to reproduce at all, but even if everyone survives there can still be plenty of variance in fitness, easily in fact since people who survive do not all have the same reproductive rate.

Going back to the suggestion that "about half the people alive today, 200 years ago would have been killed during their child years," even if this is true (and not just for the minority of humans that live in "developed" countries), there can still be plenty of variance in survival today. Thus, there can still be natural selection acting through survival (as well as natural selection acting through the reproductive rate of those who survive). In addition, there can be a kind of genetic drift powered by cultural forces and correlated traits: members of some groups of humans have higher reproductive rates (on average) than members of other such groups. Any alleles (genes) that are more common in these groups with relatively high reproductive rates will tend to increase in relative frequency in the overall human metapopulation.

One more thing to think about. Many traits are the result of trade-offs and/or balancing selection. By removing certain forces of natural selection, the equations may change. For example, natural selection may have favoured some risk-taking behaviour in young men because this might have given them a greater chance of acquiring more status and ultimately more successful reproduction. Too much risk-taking would have been counter-productive, as it would have increased mortality. The resulting behaviour might have been a balance between this benefit and this cost to risk-taking. If the benefit to risk-taking has been reduced, then the equation changes. If the cost has also been reduced, then it is hard to estimate the result.It is not at all clear why so many children seem to be suffering from certain medical problems now, and it may be purely environmental. That being said, there is no direction to evolution. Evolution is not a march towards something better, so an inheritable increase in propensity for allergic reactions would not be "a step ‘back'" in evolution.Evolution is not advancement, but certainly our genetic tinkering might eventually become an important component of our evolution (it already has in many other species).

Peez

Duvenoy

I gave this one to my girlfriend's daughter some (quite a few!) years ago. She still has it.

I found it a fascinating book. I especally liked the evolutionary role bats played. Can you imagine a large, agile, echo-locating, ground predator?

For a speculation, it was very well done.

doov

Smilin

Concerning our next 'step', extinction is a possibility.

Doubting Didymus

I think we have one tremendous advantage over most other species when it comes to extinction, which is that most of us actually don't want the species to die. Thats not something most other animals are capable of, and none of them are known to deliberately take precautions against extinction, or take an active interest in preserving the global ecosystem for future generations. There has never before been a species that wanted the whole species to survive (as opposed to just individuals, families, tribal groups, etc), and was more or less willing to take steps to defend its existance.

Lobstrosity

Yes, but there has never been a species so capable of bringing about its own demise, either. Given that a relatively small subset of humans have the power to destroy us all, it's not a given that our general desire to preserve the species will save us. For example, in one speech I heard Bush Jr give, he conceeded that global warming is occuring, but then said it would be a problem our children would have to deal with. With that kind of attitude guiding us, there's always the chance that by doing what's best for us now, we will produce a future in which human survival is not possible. Or we could just build a weapon that kills everything and actually elect someone to office who's stupid enough to use it.

Smilin

Disagreed (to some extent). Many other species possess the same qualities as the human species. That is to say, the desire to procreate, seek out food, find shelter, and deal with predators/threats (fight or flight syndrome). Only humans are vain enough to think the Earth is truly ours to do with as we like.

We poison our air, our water, dump toxic chemicals illegaly, and conduct war. This is an advantage?

Just study other species of our planet and you'll find many examples of those who work, play, and live in harmony for the benefit of the group, not the individual.

Smilin

Agreed,

No other species is guilty of taking naturally occuring biological specimens and developing them into 'weapons grade' agents deemed at mass destruction of entire populations/countries/civilizations.

Anthrax occurs naturally in Africa, humans made it into a weapon.
The Black Plague still exists, humans made it into a weapon.

Just two examples of many. Theoretically, it would only require a single event of using these 'weapon grade' biological agents which could (conceivably) eradicate the human race.. (or a major majority of it)