Does Evolution help those who help themselves?

[azzthom]

We, as a species, are getting taller. This is not due to evolution, but to improved nutrition, particularly in childhood. A measurable change in our species has occurred because of a factor we have introduced and continued to improve.
http://www.scientificamerican.com/ar...getting-taller

My question is this :- could something similar be responsible for the earlier development of our species? Could a self engineered change have caused, or more accurately assisted, our evolution to Homo Sapiens?

For example, at some point our distant ancestors discovered that fire wasn't just good for heat and light - it made meat safe, and GOOD, to eat. The use of fire for cooking opened up new food sources. Improvements in hunting techniques and technology must also have increased the amount of available food. The use of animal skins for clothing increased our protection from the elements and presumably animals. This could be quite a long list.

My point, and question, again :- Could the advances our ancient ancestors made have contributed to the evolutionary progress of our species?

It is, I believe, polite for a thread starter to offer an opinion. I hope it's clear that I think the answer is absolutely yes. I would go as far as to say that the story of human evolution from Homo Erectus onwards, is a story we wrote ourselves.

[Bikewer]

There have been those that have proposed that better nutrition may have had an effect on brain growth, but I admit I haven't kept up with any of those speculations....
If you think about it, it sounds a little like Lamark...

[Dinwar]

Well, evolution as such doesn't demand that the changes be coded into DNA--that's the annoyingly named Central Dogma. Evolution is merely change in heritable traits through time. I suppose a change in behavior can impact evolution as easily as a change in form. And it could have generated a feedback loop, where we became intelligent enough for intelligence to help in our survival, and more typical selection mechanisms reinforced what the behavioral change started.

I don't know what the data say, though. I know that people believe cooking had a major impact on our evolution, in that it allowed easier access to nutrition (it's better to eat bread than wheat, for example). A novel food source is one of the bigger drivers of evolutionary change. So it's not unreasonable. I'm just not sure we have any data one way or another.

[Earthborn]

Originally Posted by azzthom

For example, at some point our distant ancestors discovered that fire wasn't just good for heat and light - it made meat safe, and GOOD, to eat. The use of fire for cooking opened up new food sources. Improvements in hunting techniques and technology must also have increased the amount of available food. (snip) My point, and question, again :- Could the advances our ancient ancestors made have contributed to the evolutionary progress of our species?

Here's a guy arguing that, yes: humans are evolutionarily adapted to cooked food.

[Stomatopoda]

Technology changes the environment in which we live, which changes selection criteria, just like any other environmental change.

[Dancing David]

Originally Posted by azzthom

We, as a species, are getting taller. This is not due to evolution, but to improved nutrition, particularly in childhood. A measurable change in our species has occurred because of a factor we have introduced and continued to improve.
http://www.scientificamerican.com/ar...getting-taller

My question is this :- could something similar be responsible for the earlier development of our species? Could a self engineered change have caused, or more accurately assisted, our evolution to Homo Sapiens?

For example, at some point our distant ancestors discovered that fire wasn't just good for heat and light - it made meat safe, and GOOD, to eat. The use of fire for cooking opened up new food sources. Improvements in hunting techniques and technology must also have increased the amount of available food. The use of animal skins for clothing increased our protection from the elements and presumably animals. This could be quite a long list.

My point, and question, again :- Could the advances our ancient ancestors made have contributed to the evolutionary progress of our species?

It is, I believe, polite for a thread starter to offer an opinion. I hope it's clear that I think the answer is absolutely yes. I would go as far as to say that the story of human evolution from Homo Erectus onwards, is a story we wrote ourselves.

the main idea of brain development goes like this :
upright gait> narrow pelvis> increased neotany/dependence > increased brain develpment

The main issue of the ToE is reproduction anything that improves reproductive success is going to be passed on as a trait.

[Garrette]

Originally Posted by Dancing David

The main issue of the ToE is reproduction anything that improves reproductive success is going to be passed on as a trait.

Isn't there an important but often overlooked corollary?

Anything that tags along with anything that improves reproductive success is going to be passed on as a trait.

In other words, traits are not necessarily beneficial in themselves. So long as they are not detrimental they may merely be coincident with something that is beneficial.

[WhatRoughBeast]

Originally Posted by Dinwar

Well, evolution as such doesn't demand that the changes be coded into DNA--that's the annoyingly named Central Dogma. Evolution is merely change in heritable traits through time.

Umm. Could you give us an example of a change in heritable traits that is not coded into DNA? Heritability and DNA would seem, at first glance, pretty closely intertwined.

Quote:

I suppose a change in behavior can impact evolution as easily as a change in form. And it could have generated a feedback loop, where we became intelligent enough for intelligence to help in our survival, and more typical selection mechanisms reinforced what the behavioral change started.

I largely agree. Particularly in areas such as language ability and tool using.

My reservations (I did say "largely") have to do with how such changes in brain organization would lead to speciation.

Quote:

I don't know what the data say, though. I know that people believe cooking had a major impact on our evolution, in that it allowed easier access to nutrition (it's better to eat bread than wheat, for example). A novel food source is one of the bigger drivers of evolutionary change. So it's not unreasonable. I'm just not sure we have any data one way or another.

Agreed.

[Soapy Sam]

Yes. Of course.
Genes that don't interact with the environment are not subject to natural selection.
Possibly the most significant thing about humans is their degree of socialisation.
Selection for sociability probably affected brain size and structure- because it takes a pretty sophisticated brain to keep track of social relationships. Dolphins got there before our ancestors, we probably passed them about the H habilis stage . All animals engineer themselves to some extent. That's what behaviour is.

[Dinwar]

Originally Posted by WhatRoughBeast

Umm. Could you give us an example of a change in heritable traits that is not coded into DNA?

Every aspect of prion evolution. Meme theory also comes to mind. Then there are computer programs that evolve. I'm not too well-versed in epigenetics, but as I understand it a few aspects of that field aren't directly related to DNA.

Evolution doesn't require DNA to work. Evolution uses DNA in Earth-like organisms, but it can use anything that's heritable and which has variation.

Quote:

My reservations (I did say "largely") have to do with how such changes in brain organization would lead to speciation.

Step 1 would be defining the term "species", something that I really don't think can be done. I mean, after 300 years or so, it's a good guess that we can't do it. But if you go with the biological species concept, any change that causes one population to not interbreed with another population would be sufficient. Mating rituals between groups, for example.

[Robrob]

Originally Posted by Soapy Sam

Yes. Of course.
Genes that don't interact with the environment are not subject to natural selection.
Possibly the most significant thing about humans is their degree of socialisation.
Selection for sociability probably affected brain size and structure- because it takes a pretty sophisticated brain to keep track of social relationships. Dolphins got there before our ancestors, we probably passed them about the H habilis stage . All animals engineer themselves to some extent. That's what behaviour is.

You are correct. It seems once Dolphins reached that point they more or less stopped. Somehow H. Habilis continued the interaction of those genes with the environment and progressed even further. Just my opinion but I suspect it was largely because Dolphins evolved their sociability without limbs while H. Habilis evolved with limbs. The synergy of sociability + limbs leading to improved cognitive functions.

[Soapy Sam]

Originally Posted by Dinwar

Step 1 would be defining the term "species", something that I really don't think can be done.

This ^
And don't you fervently wish people who have no damn idea how to define it would stop prattling on about it as though it were some ineffable fact of nature and not a human classificatory concept?

[Dinwar]

Originally Posted by Soapy Sam

This ^
And don't you fervently wish people who have no damn idea how to define it would stop prattling on about it as though it were some ineffable fact of nature and not a human classificatory concept?

Not really. I fervently wish that the people who DO know better would stop prattling on about it as if it were some ineffable fact of nature. Once we get the experts to all agree that the dividing lines are generally arbitrary (up to a point, anyway), then I'll worry about everyone else.

[azzthom]

Thanks everyone! This is just the sort of discussion I was hoping for. I have to agree that the term 'Species' can be rather nebulous. The definition I was given at school was that ' Two individuals, are of the same species if it is possible for the to mate and produce fertile offspring'. It's a nice try, but it's also demonstrably wrong. Female mules, for example, have on rare occasions been fertile. It is also, I believe, commonly held that our own species could reproduce with Neanderthals. I even read once, though I forget where, that red hair only exists in humans as a holdover Neanderthal trait.

The only other thing I want to add at this time is that if a group of humans has learned to hunt more effectively than other local groups, they would have had a significant survival advantage over those other groups. This in turn makes our better hunters more likely to breed and pass on their better hunting techniques, as well as their genetic traits. This may, I think, be enough to at least partially explain our rapid increase in intelligence and use of language.

[Soapy Sam]

Originally Posted by Dinwar

Not really. I fervently wish that the people who DO know better would stop prattling on about it as if it were some ineffable fact of nature.

Fair point.

[Dancing David]

Originally Posted by Garrette

Isn't there an important but often overlooked corollary?

Anything that tags along with anything that improves reproductive success is going to be passed on as a trait.

In other words, traits are not necessarily beneficial in themselves. So long as they are not detrimental they may merely be coincident with something that is beneficial.

Neutral traits are often retained, but may not be spread through out members of a population because there is no selective advantage.

Yes, neutral and even detrimental traits can be retained and spread if they are associated with a beneficial trait. However, socially passed on behaviors are not going to effect the traits unless they directly impact a specific trait, that would be hard to show, and would have a likelihood of being lost.

[Soapy Sam]

Also , "beneficial", "neutral" and "harmful" are all context dependant terms.

Being vegetarian and big enough to brouse the tops of trees is beneficial, until an asteroid strike takes out the forest, at which point being small, ratlike and omnivorous may be a lot more use.

[hgc]

Interesting note on human height -- The advent of agriculture not only enabled a human population explosion as settlements and cities formed and civil stability evolved, but it led to a reduction in average height, due to the grain-based diet and a lot less meat.

[Trish Randall]

Human height has been variable throughout human history. While the ancient Romans were shorter than current Americans, the Celts of the same period averaged as tall or taller than current Americans.

Also, for the past 2 centuries, western women's heights have increased, but the difference between average male & average female heights have increased because for the past couple of centuries, western men have selected for women substantially shorter than they are.

Height of an adult human is influenced by diet, but also by genetics. I ate the same diet as my sisters, who are all at least 2 inches taller than I am.

[phildonnia]

Seems that lactose tolerance evolved in response to animal domestication:

http://en.wikipedia.org/wiki/Lactase...ionary_history

[Fishstick]

Originally Posted by Bikewer

There have been those that have proposed that better nutrition may have had an effect on brain growth, but I admit I haven't kept up with any of those speculations....
If you think about it, it sounds a little like Lamark...

I've heard/Read this more specifically that cooked food requires much less chewing, therefore requires less bulky chewing muscles and can support a smaller jaw, so leaving more room for the brain cage.

[Beerina]

Originally Posted by Bikewer

There have been those that have proposed that better nutrition may have had an effect on brain growth, but I admit I haven't kept up with any of those speculations....
If you think about it, it sounds a little like Lamark...

We also assume full nutrition is a good thing, and it sure seems to be. But we didn't evolve in a world of plenty. We evolved on a world of struggle. Growing every body part to its max potential might not be a well-buffed and optimized configiration.

We know lots of food has health problems of its own, e.g. clogged arteries that evolution had rare opportunity to work on once breeding age was past.

We know the evolved desire to cram food into your mouth becomes a liability rather than bonus. This is in addition to the confounding factor of sedentary work lifestyle, stripping the need for about 1000 calories a day from people.