Tag: evolution

Arrested development or pedomorphic edge?

It’s remarkable how much a baby ape resembles a small human. The similarity decreases quickly with age, but it does help explain how we can share so much DNA with them. In many ways we’re just slowed down versions of them. We carry that flat forehead and big brain cavity (relative to skull size) right into adulthood. I’ve often thought that chimps must look at us and shake their heads at how absurdly childish we look. Geez! These researchers, I swear they get younger every year.

In biological terms, this physical retardation goes by the name pedomorphosis or neoteny. And despite the insane length of time we have to spend sheltered by adults, we humans like to think that our childishness has treated us well. That big fat brain doesn’t blossom overnight, but when it finally pops, watch out!

A neuroscientist once explained to me that some fairly dramatic changes in brain physiology occur in late adolescence. Regions that were more plastic become more hardwired, or “burned in”. This is a reasonable biological response — your brain is saying “Hey, now that you know how things work, I can save us both a lot of time and energy by just looking up the answer on these note cards.” It’s also obvious: anyone can see that learning changes as you age, the best example of this being language acquisition. When you come to be old person, you canna learn to speaka da language… but never like a native.

On the other hand, maybe it’s time for us to let that brain be plastic a little longer. Call it Pedomorphism 2.0. After all, there’s a lot to learn these days, and it’s changing all the time. And right on cue, there is a rise in pedomorphic behavior. The average age of entry into adulthood is rising. Living at home as long as you can is a pretty sound strategy. And those extra graduate degrees may well come in handy some day.

That 28 year-old slob who plays video games all day in the basement of his parents’ house (a.k.a. Area Man)? He may well represent the future of the species. But only if he can be induced to get a girlfriend.

Kicking away the ladder: man’s fate and the Great Filter

How long have we got? Depending on who you ask, we’re roughly halfway through the time of tolerable tenure for life on Earth. The planet has been around for 4.6 billion years, give or take, and it’s got about that much more time before the swelling Sun boils our bathwater.

See the Universe Timeline for more numbers

Relatively speaking, it didn’t take very long for life to appear once the Earth had cooled down enough to support plenty of water. But notice that it took a surprisingly long time, something like 2.5 billion years (as indicated by the red bracket), before the first eukaryotic organisms came along. That’s a sizable fraction of the entire lifespan of the planet! Something extraordinary and improbable must have happened, something very lucky for us, since those little bugs were our ancestors. One way to put this in perspective is to say that, if life suddenly vanished from Earth right now, it’s reasonable to assume there would be enough time for it to develop again before the Earth was sterilized by the Sun. But it is much less likely that there would be enough time to get from simple bacteria to eukaryotic life again. On the plus side, if we simply kill off all the people, or even most of the vertebrates, there should be plenty of time to regroup and try a few more times and making something intelligent.

The latest issue of Technology Review magazine has a provocative essay by Nick Bostrom along these lines. Entitled Where Are They?, it touches on Fermi’s paradox regarding extraterrestrial life. Namely: if life in the universe is commonplace, then why aren’t we seeing any evidence of it? His conclusion is that some catastrophic event, call it the Great Filter, is blocking life on other planets from reaching the point where it can contact us. If you follow his reasoning this far, then you have to ask if the Great Filter is behind us or after us. Was, for example, the rise of eukaryotic complexity so singular, that we are the only planet in the entire galaxy to pull it off? On the other hand, what if the Great Filter is ahead of us? We, and every other planet like us, may well destroy ourselves with near certainty, either through suicidal violence or self-poisoning waste. Fossil fuel has given us wealth and a means of ascent into orbit, but we may well squander it and kick away the ladder.

It’s hard to argue with Bostrom’s reasoning. One thing that’s still not very clear to me: how likely is it that Earth-like civilizations in our galaxy would be able to hear our “leaking” radio frequency transmission? That is, not the messages we send intentionally, but just the noise we generate on a typical day. This seems to bear directly on this problem. Not much time has passed for other civilizations to hear us, but if they could hear us, then shouldn’t we be able to hear them? If we should be able to hear other civilizations as advanced as our own, but instead hear nothing, that seems pretty clear evidence that the Great Filter is behind us and not ahead of us. At any rate, I recommend you read the whole piece, if only to follow his rationale for the following comment:

If [on Mars] we discovered traces of some simple, extinct life-form–some bacteria, some algae–it would be bad news. If we found fossils of something more advanced, perhaps something that looked like the remnants of a trilobite or even the skeleton of a small mammal, it would be very bad news. The more complex the life-form we found, the more depressing the news would be. I would find it interesting, certainly–but a bad omen for the future of the human race.

By the way, Tim O’Reilly has a good piece about this same topic over at the O’Reilly Radar blog: Fermi’s Paradox and the End of Cheap Oil.

Next up for H. sapiens: Building the big bug

I recently finished Before The Dawn by Nicholas Wade, a book about the evolution of the human race which I happily recommend.

Studying the history of human development has typically drawn on things buried in the dirt: paleontological/biological artifacts like the fossilized bones in Olduvai Gorge for one example, and archaeological/cultural artifacts like the ruins of Nineveh and Route 66 for another. The problem is that stuff comes out of the dirt… very… slowly, putting a real damper on our ability to learn quickly. Wade’s book focuses on a new kind of ore, which is the living information buried in our genes and in our languages. Genetic data in particular is a fabulous gold mine for those trying to work out our past.

Surprisingly, it’s not just human DNA that’s useful. It’s possible, for instance, to work out approximately when humans started wearing clothes by genetically dating when human lice split into head-dwelling species and clothes-dwelling species. Clever! And we’re starting to get a remarkably accurate story of how humans migrated out of Africa and populated the world.

Happily, Wade is not the least bit gun-shy in talking about evidence of evolution currently under way in humans. There is good evidence that our behavior is pacifying with remarkable speed owing to the powerful adaptive advantages of law-abiding socialization. But just as evolution selects for the important, so it forgets the unimportant. Sadly, we’re shedding our sense of smell with alarming speed. A good nose makes your dinner taste good, but it’s not especially selected for. Rats can synthesize their own vitamin C, but humans lost that ability long ago. As long as you take your Flintstones vitamins, who needs to synthesize the stuff?

Obviously this all leads to the big question: what’s next? Wade doesn’t speculate much, but I will. It seems clear that modern medicine is going to allow our onboard health maintenance to get weaker and weaker. Just to pick one example: accurate, timely vaccines mean our native robustness won’t be put to the test, and that which isn’t selected for drops away. This may appear disturbing, but really what we’re doing is evolving an outboard immune system. We are offloading many heretofore intrinsic biological tasks to the next level of abstraction: the community.

This includes the outboard brain. Networks are the nervous systems for the big bug, the communal organism that we are becoming. Just as individual cells had to make some dramatic accommodations in order to form multicellular organisms, our native behaviors will be ever more conducive to hive action. We’ll sure have to get rid of all the errant terrorism genes before we can manage long term space colonies. It only takes one crazy person to wipe out a space village.

Evolution and geology

I just finished reading Sean Carroll’s book The Making of the Fittest. Subtitled “DNA and the Ultimate Forensic Record of Evolution”, it’s the follow-on book to Endless Forms Most Beautiful. In this book Carroll devotes several chapters to demonstrating how, against our natural intuition, there really is enough time (given a few hundred million years) for DNA to mutate bit by bit and still make amazing new structures like eyeballs, wings, and that pink dangly thing that hangs at the back of your mouth.

Carroll also points out that while almost everything is in flux, genetically speaking, there are some stretches of DNA so crucial to life that they never change. Which is to say, they can’t change because any variation would be fatal. Here, for example, is a six amino acid stretch that has been found in every single living thing: KNMITG. It’s an immortal sequence, unvarying across more than a billion years.

The last chapter deals with the controversies associated with teaching evolutionary theory in public schools. This is well-traveled ground, but it got me thinking about how much the opponents of evolution focus on man, monkeys, and biology class. But shouldn’t they be attacking geology too? Some of them do, insisting, for example, that the Grand Canyon formed during Noah’s flood. But it seems that a serious and consistent creationist ought to stick those little “this is only a theory” labels in every science book on the shelf. The astronomy book, the geology book, the physics book, they should all be thrown out the window along with The Origin of Species. Why is poor old Darwin always taking the heat?

Evolving robots

Read this story and you may well conclude a robot uprising is right around the corner.

Carl Zimmer’s recent post Evolving Robotspeak describes robotics research done by social evolution researcher Laurent Keller in Switzerland. Plenty of folks have used genetic algorithms to “breed” robots, but this is the first time I’ve heard of someone using family and colony models for their genetics. In a nutshell, if you breed individual robots to find virtual food, they quickly get trained to do pretty well. But if you breed them as families, they do even better. To put it in anthropomorphic terms, their intermingled genetics help them understand the value of cooperation.

It’s fascinating to see the genetic theories of social behavior borne out in a colony of robotic organisms. This Darwin guy may have been on to something after all.

The big brain

I was recently reading Sean Carroll’s excellent book on evolutionary developmental biology, Endless Forms Most Beautiful, in which he says that “brain size [in humans] roughly doubled in a million years.” This was a dramatic (and expensive) departure in the brainweight-to-bodyweight ratio compared to all other mammals. Carroll goes on to say:

The brain is a very expensive organ in terms of energy consumpution, drawing up to 25 percent of an adult human’s energy (and 60 percent of an infant’s).

Who knew the brain was such a hog? You can rest your legs and unshoulder your weary load, but your brain keeps drawing current rain or shine. And a good thing too. An evolutionary stockbroker might describe the relationship between the brain and the evolutionary fate of Homo sapiens as this: an expensive investment, but ultimately worthwhile.

These words were in my head as I recalled some articles I was reading about the growing electrical appetite of data centers. It turns out that data centers and server farms are sprouting like mushrooms along the Columbia River in Washington and Oregon. Why? Because that’s where the cheap hydroelectric power is. These giant computing centers, erected in rapid succession by Google, Yahoo, Microsoft, and others are hot, hungry, and growing fast. The electrical power consumed by computers has become one of the most significant costs of a modern corporation, particularly since it has the knock-on expense of driving cooling costs too. Electrical companies joke about giving away computers and making up the cost on juice.

Who knew the computer was such a hog? We can regulate our trucks and trade in the Hummer for a Prius, but the great Google brain keeps drawing current rain or shine. Every day, as we commune by keyboard with the net, banging out our neuron’s part, the network is evolving.

I’m guessing it’s an expensive investment, but ultimately worthwhile.