Thursday, April 28, 2011

Public Safety Announcement: Get the f- out of the passing lane

Just a friendly reminder to anyone who drives on the interstate: THE LEFT LANE IS FOR PASSING OTHER CARS.

I'm in impatient but also practical person, and there's little else in the world that makes me more furious than being trapped behind someone abusing the left lane. On the one hand, it's simply annoying when you cannot go a preferred speed (the speed limit or faster) because some bastard is just hanging out in the left lane not passing anyone. But on the other hand, it also obstructs traffic and can be dangerous.

Traffic in the right-most lane has a greater likelihood of being sub-fast-enough because cars are entering or exiting the highway (ramps!). If a car needs to merge onto the highway, common courtesy (actually I think the law) demands you move over to the left lane to allow this newb onto the highway - this is impossible when some buttsack is parked in the passing lane and prevents you from moving over without dangerously speeding up or slowing down.

In addition, when people get trapped behind slow traffic in the fast lane they often become impatient and begin trying to pass on the right side of cars. This is also dangerous for the reasons outlined above - people may need to get right to get off the highway and even knowledgable drivers generally won't expect to be passed on the right.

The passing lane has the misnomer "fast lane." This is due to the fact that generally when you're passing someone it means you're going pretty fast. IT DOES NOT MEAN YOU CAN SIMPLY DRIVE IN IT BECAUSE YOU'RE GOING OVER THE SPEED LIMIT. If you're going 75 in a 70 zone but the traffic behind you is coming along at 80, you need to move over as soon as you can.

Also if there are people parked on the right shoulder, it's the law (as well as safe and courteous) to move to the left lane as you pass, if possible.

So please please please if you're not passing another car, get the GDF out of the left lane.

Thank you.

Tuesday, April 26, 2011

Is eugenics really dead?

My advisor passed along a USA Today story about the eugenics origins of the journal Annals of Human Genetics. Eugenics was a popular movement in the early 20th century, in which people thought it wise to take the onus of natural selection upon themselves, to encourage smart wealthy people to breed and 'dullard' poor folk to be sterilized. The movement was based on a misunderstanding of evolution, heredity and the genetic basis for complex traits like 'intelligence' (whatever the hell that term really means). Not to mention a sense of intellectual and moral superiority among moneyed white people. Eugenic thinking is what underlay the reprehensibly regrettable misgivings of the Holocaust.

I think it's great that the Annals of Human Genetics is public about the journal's off-color origins. Anthropology itself (and not just the biological subfield, don't let any cultural anthropologist let you think otherwise [yes I have a specific person in mind here]) was borne of Western countries going off to figure out why the lands they were colonizing and exploiting contained humans that differed from themselves (as well as how to deal with 'inferior races'). It's important to know of your field's past mistakes, lest history repeat itself.

Is it repeating itself? Nowadays, people can get 'genetic counseling' if they're contemplating pregnancy, to learn their purportedly genetically predisposed risks for having a child with certain conditions like Down Syndrome. With such knowledge, people can elect not to have kids together. Is this a blessing from medical genetics, or are we seeing a resurgence of biological determinism and old school eugenics?

Monday, April 25, 2011

What big teeth you have, indeed

If our friend Little Red Riding Hood was dumb enough to've thought a wolf in babushka threads was her grandma, well, she probably would have played Bingo with a grandmother-mimicking Australopithecus anamensis.

Australopithecus anamensis is the earliest undisputed hominid, found in deposits ranging from 4.2 - 3.9 million years ago in Ethiopia and Kenya (Leakey et al. 1995, White et al. 2006). Now, hominids are allegedly distinguished from other apes by having relatively short canine teeth distinguished by having relatively tall 'shoulders,' creating a diamond-shape in front view. Nevertheless, compared with humans these early australopiths had pretty murdersome canines, within the range of female chimpanzee species. (my dictionary is trying to tell me 'murdersome' isn't a word, but I learned long ago not to learn right and wrong from a book)

Such canine form - relatively small with tall shoulders - was important in diagnosing Ardipithecus ramidus (> 4.4 million years) as a hominid back in the roaring 1990s (White et al. 1994). Of course, we learned in the 1980s that many ancient fossil apes looked superficially like hominids because of dental similarities, the result of either parallel evolution or hominids' retention of primitive features. Indeed, even in light of the recently described Ardipithecus ramidus skull and skeleton, the main similarities with later, undisputed hominids are dental.

With this in mind, I'm struck by the canine of Nakalipithecus nakayamai, an ape from Kenya dating to nearly 10 million years ago (Kunimatsu et al. 2007). This is ape was a pretty important discovery because it began to fill in a rather lonesome Late Miocene ape fossil record in Africa. So, below is a picture of Nakali and anamensis canines, which I've tried to properly scale with the cutting-edge techniques of Microsoft Powerpoint (that is absolutely not a plug for Microsoft). On the left is Nakalipithecus, and the 2 on the right are Au. anamensis. The middle one is anamensis from Asa Issie in Ethiopia, and is the largest canine found of any hominid, ever I think. On the right is anamensis from Kanapoi in Kenya, not as big but sharp as shi... kabob skewers. Well crap, the "hominid feature" of short canine crown with nice shoulders is found in this 10 million year-old ape!

Two mutually exclusive scenarios could explain this similarity: [1] this canine morphology truly is a shared-derived feature of hominids, but hominids and Nakalipithecus just happened to evolve the same morphology independently for no better reason than, say, ennui. [2] This morphology is the ancestral condition for hominids (and chimpanzees and possibly gorillas). The fanciest cladistic methods won't resolve this issue, only the discover of more badass fossils will. But if [2] is correct, that would deal a tough blow to the case of Ar. ramidus (and Sahelanthropus) behing a hominid. Really, it seems like the distinguishing feature of early hominids was their deplorable lack of distinguishing features.
Oy, if bones and teeth are prone to homoplasy (similarity due to parallel evolution and not because of common ancestry), could paleoanthropologists have a special proclivity for it, too (that is, in naming dental hominids)?

Further reading!
Kunimatsu, Y., Nakatsukasa, M., Sawada, Y., Sakai, T., Hyodo, M., Hyodo, H., Itaya, T., Nakaya, H., Saegusa, H., Mazurier, A., Saneyoshi, M., Tsujikawa, H., Yamamoto, A., & Mbua, E. (2007). A new Late Miocene great ape from Kenya and its implications for the origins of African great apes and humans Proceedings of the National Academy of Sciences, 104 (49), 19220-19225 DOI: 10.1073/pnas.0706190104

Leakey, M., Feibel, C., McDougall, I., & Walker, A. (1995). New four-million-year-old hominid species from Kanapoi and Allia Bay, Kenya Nature, 376 (6541), 565-571 DOI: 10.1038/376565a0

Ward, C. (2001). Morphology of Australopithecus anamensis from Kanapoi and Allia Bay, Kenya Journal of Human Evolution, 41 (4), 255-368 DOI: 10.1006/jhev.2001.0507

White, T., Suwa, G., & Asfaw, B. (1994). Australopithecus ramidus, a new species of early hominid from Aramis, Ethiopia Nature, 371 (6495), 306-312 DOI: 10.1038/371306a0

White, T., WoldeGabriel, G., Asfaw, B., Ambrose, S., Beyene, Y., Bernor, R., Boisserie, J., Currie, B., Gilbert, H., Haile-Selassie, Y., Hart, W., Hlusko, L., Howell, F., Kono, R., Lehmann, T., Louchart, A., Lovejoy, C., Renne, P., Saegusa, H., Vrba, E., Wesselman, H., & Suwa, G. (2006). Asa Issie, Aramis and the origin of Australopithecus Nature, 440 (7086), 883-889 DOI: 10.1038/nature04629

Thursday, April 21, 2011

Humans, kinda like rabbits

It's been quiet at Lawnchair for a while, I've got my prelim exams (to become a candidate) coming up really soon, and I've been working on honing the topic of my dissertation (which is generally in a more fiery, furious and constant state of upheaval than the Earth's inner-workings).

One thing I'm looking at right now, though, that I thought I'd share is how much human population size has increased in just a few thousand years. Below is a figure from John Hawks and colleagues (2007) on recent natural selection in modern humans (see also my post on evolution and why we're still evolving).
Note that this is only part of the human population - it doesn't include East Asia or the Americas. In addition, population size is on a logarithmic scale, so that each tic is an increase in order of magnitude. 30 thousand years ago there were probably only some 1.5 million people on the continents of Europe-West Asia and Africa. Those numbers slowly increased until around 10 thousand years ago, about when humans began farming. From there, population sizes sky-rocketed, such that there currently probably over 2 billion people on these continents alone. The global human population is estimated to number over 7 billion people right now. Seven billion - a number so unfathomably large you and all your friends couldn't count that high before you expire (not to mention get bored from counting for no reason).

Our superlative success as a species is at once astounding, as well as disconcerting. Most animals reproduce at a rate such that their population sizes are either steady or declining over time. I want to say I've seen a figure somewhere to the effect that chimpanzee survival and reproduction rates are such that their numbers are likely declining. We, on the other hand, are reproducing like rabbits, to use the old saying. Have we figured out a way to circumvent the Malthusian constraint of limited resources in an expanding population? Or do we have yet to fall victim to our excessiveness?

On a lighter note what's cool about this study is it shows that as a species we've experienced a great deal of natural selection in very recent times. This amount of evolution was made possible because our exploding population sizes, which meant the introduction of greater amounts of new mutations each generation, increasing the likelihood than an adaptive one pops up. Plus our social and food-gittin' lives introduced us to new selective pressures most of our ancestors probably didn't face, like crowded living conditions, first with more people and later with animals. We just might be an egregious experiment in extreme evolution.
Hawks, J., Wang, E., Cochran, G., Harpending, H., & Moyzis, R. (2007). Recent acceleration of human adaptive evolution Proceedings of the National Academy of Sciences, 104 (52), 20753-20758 DOI: 10.1073/pnas.0707650104