Philosophy Discussion Forums

Dysorganism wrote:My guess is that human evolution is faster now than ever before. As many have pointed out evolutionary success is to have the maximum number of fertile offspring. Palaeolithic humans were well adapted to their environment. There were probably few new genes that gave a strong selective advantage. The reproductive strategy was to have few children, invest heavily in raising each child and to have low child mortality compared to most other species.

Not sure how you arrived at that conclusion about human evolution being faster now. Almost everyone in developed countries live long lives, so there's less selective pressure than there used to be. And the human population is huge compared to the olden days, so evolution is going to be slower than then. As a simplified example, say the human population was down to ten people. Any survival characteristic is going to be heavily adopted in the next generation and all the generations after that, whereas nowadays it would get mostly lost in the general population.

Poor people around the world have large numbers of children compared to affluent families. I'm pretty sure hunter-gatherer mothers were popping out babies right and left. Family planning wasn't an advanced science, and it was high infant mortality that kept the number of surviving offspring down. In African countries today women have huge numbers of kids because of their high mortality rate so they'll have enough children to take care of them in old age, and I suspect that it was the same in prehistoric times.

But I suspect that wasn't your point, exactly. I do believe that each species arrives at the optimum number of offspring per mama. In the case of humans, the babies require tremendous and prolonged care by the mother, because in order to develop the brainpower that gives them their survival advantage, it's a slow process and involves learning from the elders.

enegue wrote:

Dysorganism wrote:My guess is that human evolution is faster now than ever before. As many have pointed out evolutionary success is to have the maximum number of fertile offspring. Palaeolithic humans were well adapted to their environment. There were probably few new genes that gave a strong selective advantage. The reproductive strategy was to have few children, invest heavily in raising each child and to have low child mortality compared to most other species.

You don't think that hunger, violence and disease might have played the significant role in the keeping population numbers depressed?

Cheers,
enegue

No, I do think hunger, violence and disease kept populations down. I'm just saying that compared to most other species mortality was probably still low. If not we would not have been here today. With all the effort it takes to raise and educate a human child, humans just can't afford to have enough children to compensate for a mortality rate as high as most other species. The other extreme is a species like frog that lay thousands of eggs and the lets the tadpoles fend for themselves.

Tomas

Wilson wrote:

Dysorganism wrote:My guess is that human evolution is faster now than ever before. As many have pointed out evolutionary success is to have the maximum number of fertile offspring. Palaeolithic humans were well adapted to their environment. There were probably few new genes that gave a strong selective advantage. The reproductive strategy was to have few children, invest heavily in raising each child and to have low child mortality compared to most other species.

Not sure how you arrived at that conclusion about human evolution being faster now. Almost everyone in developed countries live long lives, so there's less selective pressure than there used to be.

My point was that evolutionary success is not just about not dying it's also about having many offspring. Surviving in a paleolithic environment is something we are adapted for. But we are not adapted for maximizing number of offspring in an environment were almost all survive.

Let’s say there is a gene called tenplus. Everybody that has the tenplus gene gets more than ten children. It's not hard to see that in a modern environment with low mortality the tenplus gene would be quite successful and humanity would change. If you accept that reasoning you have to admit that evolution is at least theoretically possible even if mortality is low.

I don’t expect there to be a tenplus gene. But I think there are genetic variants that will favour reproduction.

Wilson wrote: And the human population is huge compared to the olden days, so evolution is going to be slower than then. As a simplified example, say the human population was down to ten people. Any survival characteristic is going to be heavily adopted in the next generation and all the generations after that, whereas nowadays it would get mostly lost in the general population.

I don't remember that much about how population size affect evolution rate. But I’m sure it’s not that simple. In a larger population the rate of new beneficial mutations entering the population is higher. The likelihood of a beneficial mutation becoming fixed in the whole population is still quite high. Once the mutation has reached a high enough number of individuals it is not likely to disappear and the survival advantage will push it to become fixated in the whole population. Then there is genetic drift. New neutral mutations spread and become fixed by chance. Genetic drift will be affected differently by population size. A Populations genetic makeup always change even without selection pressure. Species are often comprised of many population with some sharing of genes. Population size and evolution rate is really complex

Wilson wrote: Poor people around the world have large numbers of children compared to affluent families. I'm pretty sure hunter-gatherer mothers were popping out babies right and left. Family planning wasn't an advanced science, and it was high infant mortality that kept the number of surviving offspring down. In African countries today women have huge numbers of kids because of their high mortality rate so they'll have enough children to take care of them in old age, and I suspect that it was the same in prehistoric times.

I think hunter-gatherer societies practice more birth control than agricultrual societies. But I cant give you a source.

enegue wrote:

Dysorganism wrote:My guess is that human evolution is faster now than ever before. As many have pointed out evolutionary success is to have the maximum number of fertile offspring. Palaeolithic humans were well adapted to their environment. There were probably few new genes that gave a strong selective advantage. The reproductive strategy was to have few children, invest heavily in raising each child and to have low child mortality compared to most other species.

You don't think that hunger, violence and disease might have played the significant role in the keeping population numbers depressed?

No, I do think hunger, violence and disease kept populations down. I'm just saying that compared to most other species mortality was probably still low. If not we would not have been here today. With all the effort it takes to raise and educate a human child, humans just can't afford to have enough children to compensate for a mortality rate as high as most other species. The other extreme is a species like frog that lay thousands of eggs and then lets the tadpoles fend for themselves.

Tomas

Wilson wrote:

Disorganise wrote:My guess is that human evolution is faster now than ever before. As many have pointed out evolutionary success is to have the maximum number of fertile offspring. Palaeolithic humans were well adapted to their environment. There were probably few new genes that gave a strong selective advantage. The reproductive strategy was to have few children, invest heavily in raising each child and to have low child mortality compared to most other species.

Not sure how you arrived at that conclusion about human evolution being faster now. Almost everyone in developed countries live long lives, so there's less selective pressure than there used to be.

My point was that evolutionary success is not just about not dying it's also about having many offspring. Surviving in a paleolithic environment is something we are adapted for. But we are not adapted for maximizing number of offspring in an environment were almost all survive.

Let’s say there is a gene called tenplus. Everybody that has the tenplus gene gets more than ten children. It's not hard to see that in a modern environment with low mortality the tenplus gene would be quite successful and humanity would evolve to have more children. If you accept that reasoning you have to admit that evolution is at least theoretically possible even if mortality is low.

I don’t expect there to be a tenplus gene. But I think there are genetic variants that will favour reproduction.

Wilson wrote: And the human population is huge compared to the olden days, so evolution is going to be slower than then. As a simplified example, say the human population was down to ten people. Any survival characteristic is going to be heavily adopted in the next generation and all the generations after that, whereas nowadays it would get mostly lost in the general population.

I don't remember that much about how population size affect evolution rate. But I’m quite sure it’s not that simple. In a larger population the rate of new beneficial mutations entering the population is higher. The likelihood of a beneficial mutation becoming fixed in the whole population is still quite high. I think a larger population increases the speed of adaptive evolution.

Then there is a different mechanism called genetic drift. Drift is when new mutations without survival value spread and become fixed in a population by chance. A large population size may make it harder for drift to happen.

A population’s genetic makeup always change even without selection pressure. Species are often comprised of many populations with some sharing of genes. The relation between population size and evolution rate is really complex.

Tomas

Quoting a post by A Poster: "If we start directly engineering our own genome at the molecular level, then I'd say we'll have sped up evolution quite a helluva lot."

Actually, we're already doing this but negatively and "unintentionally" by fouling our environment (and increasingly so) with pollutants that cause human genetic mutations and decrease human fertility (e.g., synthetic chemicals that mimic biohormones) - hardly a desirable form of evolutionary pressure.

"If we begin to carry our own artificial environments into space and disseminate our genome off-world, we will certainly be leapfrogging over what evolution without her human component could do."

Yes, after we succeed in making this planet a wasteland unfit for human habitation we may survive long enough to move on to our next garbage dump. I'm being somewhat facetious - only somewhat.

An obvious quote by Obvious Leo: "However on the plus side, fewer humans die at the hands of other humans than ever before in human history, so we have reason to be optimistic about the information age we're entering into."

I distrust the statistic, especially if one includes all the novel new ways mankind now has of killing his fellow man and/or shortening his/her lifespan and curbing his/her reproductive capacity: a wide variety of weapons of mass destruction and the chemical warfare of the aforementioned industrial pollutants.

Gee, I'd better stop now, I'm starting to sound like a cynic....

You're a gloomy sod, Felix, but I fear you may be right. The survival value of human intelligence has never been satisfactorily demonstrated and there is good reason to suppose that any civilisation which develops the capacity to destroy itself will inevitably do so.

I guess the question then becomes. How do we avoid our fate?

Regards Leo

"How do we avoid our fate?"

Just what should be obvious: Behaving intelligently and mentoring our children to do likewise, considering how our actions will affect future generations, stop rewarding abject selfishness, greed, avarice, sloth, etc.

Leo, Care to reply to the responses made to your comments in this thread? = "How can an infinite universe have origins?" It's an interesting dicussion, thank you.

Felix wrote:Just what should be obvious: Behaving intelligently and mentoring our children to do likewise, considering how our actions will affect future generations, stop rewarding abject selfishness, greed, avarice, sloth, etc.

The obvious is always good with me, Felix, so our future looks assured.

I got a bit disheartened with the infinite universe thread because few posters here seem inclined to talk about either physics or metaphysics, both of which are subjects very dear to my heart. If one is willing to cling to the belief that the universe had a beginning then one must also accept the existence of an external causal agent, which is not to my conceptual taste. However I have no inclination to bandy meaningless words with those who take a different view based solely on faith, because by doing so they deny that reason has a role to play in the comprehension of our cosmos. I feel I have a right to expect better in a philosophy forum and have therefore been spending my time more fruitfully in the garden of late.

Regards Leo