It's widely understood that there are many different species of monkeys and apes. And most Americans (at least of my generation - I'm not sure what schools are teaching now) are aware that there have been various species of humans in the past. There's a tendency to think that the development of humanity was a neat, orderly progression, but it didn't work that way.

Stephen Jay Gould introduced the idea of "punctuated equilibrium", which is to say that evolutionary change is relatively calm until something comes along to stir things up. A common culprit is climate change, and the occasional meteorite can radically change the game.

I recently picked up a book by William Calvin called The Ascent of Mind, which builds a case that human evolution took off 2.5 million years ago due to a severe ice age. We know about the ice age through studies of rock and soil layers dating back to that time, and an examination of fossil skulls before and since show sharp growth in brain capacity at the 2.5 million year point.

Calvin published his book in 1991.

Today I came across this:



As you can see, it shows the various forms humans have developed in the past, where they are on the timeline, and the spike in cranial capacity after 2.5 million years. You can also see that some species didn't make it. Actually, NONE of them made it to the present time, except ours.

There's a lot of debate about why. Perhaps some previous species were more susceptible to a particular disease, or couldn't compete with other competing human species, couldn't adapt to climate changes, or simply had a run of very bad luck. Millions of years ago, hominins didn't number anywhere near like we do now; a entire species could be concentrated in a relatively small part of the African Rift Valley. It wouldn't take a huge event to wipe them out.

Today humanity numbers over six billion strong. We may owe a lot to an ice age that bred a meaner, tougher, smarter ancient ancestor.

The question sums up a problem that has always puzzled game theorists. From the article:

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It’s a truth borne out in biology and economics: Selfishness pays. Viruses can steal enzymes to reproduce. Tax evaders can take advantage of public services to survive and thrive. And, according to game theory, the cheats win out over the altruists every time.

Yet cooperation is a hallmark of human society, allowing for the creation of everything from the local grange to the United Nations. Cooperation can also be found in the animal world. Lions hunt in packs. Ants and bees create colonies. So how could cooperation evolve in a cheater’s world?

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Three researchers at Brown University think they've hit on the answer. I've always been interested in this question, and their theory sounds entirely plausible and can probably be tested.

http://www.sciencedaily.com/releases/2006/06/060629230929.htm

I have just one quibble with the piece, and it's their use of the term altruism. I've never believed that altruism = unselfishness.

Altruism is another survival strategy, based on the cooperation model. It is ultimately selfish (in the sense of looking out for one's own interest, not in the sense of taking unfair advantage of others) in that the person practicing altruism aims to encourage broader cooperation, and benefit from that cooperation.

That's a perfectly valid and sensible strategy, and this article examines how it works.

Here's a toast to PZ Myers' blog, Pharyngula. He's a professor of biology in Minnesota, and recently posted a link to this multimedia timeline of evolution. Just grab that red arrow with the mouse and move it along. I've been checking in with PZ's blog for a few years now, and he just keeps getting better.

Jen & I attacked the apartment yesterday with the vacuum and steam cleaner. We took the joint apart, parked it outside in the breezeway, cleaned up and put everything back together. Not quite as extensive as moving, but close. It was a long day, but worthwhile. Between that and the new air filter in the A/C, the place smells a lot sweeter and cleaner.

An excellent evolutionary timeline that provides a great sense of scale for the development of life. Just scroll down the page a bit to see it. Then start scrolling right...and scrolling...and scrolling...

http://andabien.com/html/words/evolution-px.htm

Well...kinda-sorta. It's like this...

The earth is roughly 4.5 billion years old, but complex (multi-celled) life didn't appear until about 500 million years ago.

That is, for nearly 90% of earth's existence, single-celled life was the only game in town. I've always wondered - why did it take so long for multi-celled life to emerge?

Scientific American has some tantalizing new research that may explain why.

To sum it up...

We already know that part of the reason is oxygen. Prior to 500 million years ago, there wasn't a lot of it. What did exist was slowly being generated by the single-celled critters.

But it appears that maybe there was another factor - clay, the stuff of kitty litter. Turns out, clay was being created by chemical weathering, the interaction of single-celled life and rock. That's right - bacteria munching on rock.

(Rock eating bacteria is still around. They eat v e r y s l o w l y - requires lots of chewing, I suppose).

Again, it takes a long time - literally hundreds of millions of years, maybe a few billion - for enough clay to pile up for it to influence the atmosphere.

The thinking is, as the clay accumulated, it trapped organic carbon. As carbon declined, oxygen rose - eventually to where a tipping point was created about 500 million years ago - enough to sustain multi-celled life.

You could say it simply took a long time for the earth to reach a point where something more than algae and bacteria could breathe. Clay was the key.

It's not definitive, but the evidence described in the article is compelling. Maybe the gods really did have clay feet!

- K

A new court case, Kitzmiller v. Dover Area School District, begins Monday. A group of parents sued the Pennsylvania school when the board mandated a statement in support of "intelligent design" for biology classes. The outcome will have profound implications for education in America, so this case bears watching. It's expected to last about five weeks.

Reading about the case reminded me of something I wrote a while back, before I began blogging. I'm sharing it here.

For a number of years now, Creationists have attempted to depreciate the value of evolutionary theory by condescendingly referring to it as "just" a theory, and suggesting that it is incomplete.

The best response to that is - OF COURSE it's incomplete. Of course we are still learning more about how evolution works. It's only within the past five years that we've been able to decode the complete genome of living creatures. There is still much to learn.

But evolutionary theory has already taught us a great deal. It beautifully explains how bacteria and viruses mutate and adapt to new environments, acquiring along the way potent new forms of resistance. This insight has helped us understand how to combat pathogens that are harmful and deadly to us.

What has creation theory contributed to our understanding of disease?

Nothing.

Creationists are fond of saying that no one has ever seen a new species evolve. This is simply because the pressures of natural selection occur over long periods of time. Hang around long enough and you WILL see new species evolve.

But if you'd like to see a model of natural selection in everyday life, you need look no farther than the nearest dog. Every dog alive today is descended from wolves. Their astonishing variety, from toy poodles to German shepards, from pit bulls to St. Bernards, are not due to natural selection, but through human deliberation, the result of centuries of breeding for specific characteristics.

In the process of natural selection, environmental pressures rather than humans eliminates individuals lacking some essential survival trait and preserves those who have them.

Over staggering time spans, environments change, alternating between times of plenty and harsh times of scarcity, with fierce competition for resources. Life perseveres by changing form to match existing conditions.

The scientific method begins with a question - "How does the world really work?" - and collects facts that help answer the question.

When patterns emerge from assembled facts, we start making predictions based on those facts.

Scientists have been confirming Einstein's predictions based on his theory of relativity for years and consistently find his guesses were right. The predictive power of science dwarfs that of any prophet.

What Darwin did was gather facts about the geological record, the fossil record and creatures living today. Taken together, a clear pattern emerged. He presented evidence that life has been adapting and changing for hundreds of millions of years, and the facts amassed since his time overwhelmingly support his theory.

Where science begins with a question, creationism begins with an agenda.

Creationism turns the scientific method on its head by starting with a theory - that the world was created and ordered by a supernatural being - and then looking for facts to support it, discarding any facts that inconveniently fail to fit the theory.

This approach does such violence to the scientific method that it isn't even worthy of being called science, and certainly isn't deserving of a place in our scientific curriculum.

Creationists understand this. The creationism debate isn't really about evolution. It's about supplanting science with religious dogma. It's about exchanging hard-earned understanding that is open to review and testing by all for received "wisdom" that is handed down from authority and must not be questioned.

There was a time once before when this trade was made. We call it the Dark Ages.

The city of Dayton lies an hour out of Knoxville, a town that evokes the
Mayberry-50's era, and remains best known as the setting of the Scopes
Monkey Trial in the summer of 1925.

The trial famously pitted evolution theory against religious
sensibilites, and ended with a conviction of the teacher who supported
science. It was the OJ trial of its day, with top-notch lawyers and
continual publicity.

We drove out hoping to see the Scopes Trial musuem last Saturday, but
turns out it's closed on weekends. The downtown area is nearly absent of
people and activity, and the grounds of the old courthouse are littered
with the leaves of fall. Only a tiny sign announces the existance of the
museum, as though the locals feel ambivalent about this historical
event.

Jen & I lingered long enough to walk around the building and take a few
snapshots. We'll have to visit the musuem virtually on the Net. But even
a jaunt out of town amid the Tennessee mountains is a worthwhile trip by
itself.


( 5 images )


Another account of a visit similar to ours can be found
here

In the course of my work at a psychiatric care center, I've often observed how deeply rooted the manipulation of other people is in human nature. It's part of who we are, if not our best side.

Turns out that's even more true than I imagined. Science journalist and author Carl Zimmer comments on a new study that clarifies the relationships between deception, social intelligence, and brain size.

It's long been noticed that social mammals have the largest brains. This study makes a convincing case that social interaction actually drives brain expansion and intelligence overall. It notes that homoid brain sizes have expanded in sync with the increasing tendency for people to gather in large groups.

It makes sense, it passes the common sense smell test. Dealing with people is demanding. Identifying, attributing (good or bad, friend or foe, trustworthy or unreliable?) remembering those attributes, competing, cooperating.

Neural density and intelligence may very closely correlate with human density.

This could explain why large urban areas mostly vote Democratic ;)

Check it out - Zimmer is a pleasure to read. His style is much like Jared Diamond.

http://www.corante.com/loom/archives/004685.html

Swiped from JWZ:


Richard Wrangham: The Evolution of Cooking

"We always tend to think that humans have just had a continuous surge in brain size over the last two million years, but actually over the last thirty thousand years brain size has decreased by 10 to 15 percent. [...] This gracility is exactly the same pattern we see in the evolution of dogs from wolves, or bonobos from chimpanzees, or domesticated foxes from wild foxes. In all these cases an increasing gracility of the bone is an incidental effect.

I think that we have to start thinking about the idea that humans in the last 30, 40, or 50 thousand years have been domesticating ourselves. If we're following the bonobo or dog pattern, we're moving toward a form of ourselves with more and more juvenile behavior. [...] I think that current evidence is that we're in the middle of an evolutionary event in which tooth size is falling, jaw size is falling, brain size is falling, and it's quite reasonable to imagine that we're continuing to tame ourselves."

RICHARD WRANGHAM is a professor of biology and anthropology at Harvard University who studies chimpanzees, and their behavior, in Uganda. His main interest is in the question of human evolution from a behavioral perspective. He is the author, with Dale Peterson, of Demonic Males: Apes, and the Origins Of Human Violence.