Arnold Kling  

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On page 139 of Second Nature, Haim Ofek writes,

In close analogy with the female role in sex selection, customers (of both sexes) seem to be highly inquisitive about the merchandise they seek to acquire; thus collecting information, checking warranties, sorting for quality, trying for sized and color - always comparing prices with alternative retail outlets...Vendors, on their part, act in analogy closer to the role of the male. First they try to eliminate competition from their own ranks, sometimes to the point of cut-throat price wars. Then, they spend a fortune on display and advertisement.

This is an aside. Ofek is concerned with the origin of market exchange, and he considers but rejects the possibility that it somehow emerged from sexual selection. Still, that paragraph alone is something one could discuss in a book club for several hours.

Of all of the books that I have read in the past two years, this is the one I would most like to discuss in a group. Part of the reason is that I never took a course in evolutionary biology, so much of the material is unfamiliar to me. Anyone in the DC area who would like to read it and discuss it is welcome to leave a comment.

The main thesis of the book is that humans are unique in that they engage in market exchange (as opposed to nepotistic exchange, which is engaged in by other species). This capability makes demands on the brain, and as humans competed with one another their brains evolved to become ever larger, just as giraffes competing with one another caused the giraffe neck to become longer and longer.

I first posted on the book here.

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COMMENTS (22 to date)

You're making me want to read yet another book here. Especially as I am familiar with the evolutionary biology stuff.

Actually, there is a species that engages in a kind of barter that comes close to in-group market exchange: the bonobos, or pygmy chimpanzees (which are also genetically our closest relatives). And
what do they use as their medium of exchange? Sex. Actually, they use sex to greet each other, to ease tensions, as trade for something they want, or as something to do when bored. They have also been observed to trade one good for another, though.

Matt writes:

A pack of wolves, surrounding a prey. This is a market mechanism, and exchange of territory with fellow hunters, a sense of the overall pack, and the target.

Squirrels sharing a tree.

I guess I need more specifics, or else I have to read the book.

Matt writes:

OK, I will try to drop notes as I read, which may be unfair to the author.

First, Australopithecines. These folks still migrated along seasonal paths, they ate from trees and probably trapped small animals.

Their migration paths have become littered with haphazard orchards of their favorite fruit, as they stopped at watering holes on a regular basis and spit out seeds.

When did they discover this pattern? Very early, but their discovery became, and is becoming clearer as evolution rolls along.

I will bet that early one, even these folks were gestering to the tribe about where the best place to spit seeds might be.

Matt writes:

One last note, but this thread should continue.l

The founders effect is fundamental, and I look, for this, as you know, whenever I deal with an essay that starts from evolution.

The founders effect says that evolution operates like a mathematical Schur reduction of an undifferentiated process. Evolution looks at the main, udifferentiated instinct, and slices off a portion of that into a residual instinct, one that can stand on its own and represents a small port on of the original undifferentiated instinct.

Not an expert, but I guess that genetic algorithms on computers can be analyzed as Schur reductions.

It means that our instincts end up as unbalanced hierarchical tree structures. At the current moment, we are dominated by the last "eigen vector" evolution pealed off and the remaining, slightly less undifferentiated noisy instinctual mass.

Matt writes:

Sorry, one more.

Brad (DeLong) posted a paper on early medeival agriculture that shows humans could knowingly get excellent, nutrient balanced, wheat yields as far back as 1,000. Very important, it shows how much more we know about agriculture and how early, but we don't do it when another constraint reduces utility.

Also, one of the most important aspects of free markets -- property rights -- goes all the way back to territorial fishes, who protect a piece of territory for reproductive purposes. So the need to have and protect one's own property is not found in the human brain, the mammal brain, or the reptilian brain -- but in the fish brain we all still retain!

The Sheep Nazi writes:

Making a Living in the Middle Ages, by Christopher Dyer, is a pretty good read w/ respect to medieval agriculture and especially the politics of it.

Stan Greer writes:

Arnold Kling, you really need to pick better analogies. The evidence that giraffe's necks got long as a result of natural selection is nonexistent. And you don't have to be a proponent of creationism of any kind to recognize that fact.

If economists don't wish to apply their critical thinking skills to biological questions, perhaps they should steer clear of them. Unthinking acceptance of the conventional academic wisdom about biology leads one to make absurd statements.

See for more information.

Giraffe's necks got long due to a change in neck bone development rates -- a change in a developmental protein. Now, this did undergo natural selection, as those that had longer necks (and legs) could reach leaves others couldn't -- not to mention that the mere size of a giraffe is a deterrent to lions and leopards.

Steve Sailer writes:

Don't chimps exchange services, typically picking lice out of each other's fur, and tend to keep track of who did what for whom? Chimp faces are very idiosyncratic, so they can identify each other by sight.

Yes. This is typically done for the social purpose of keeping and maintaining political alliances. It's literally "If you scratch my back, I'll scratch yours" -- and side with you if anyone challenges your position in the troupe. This is perhaps why we feel more comfortable with political decisions rather than allowing the free market to work, even if we know intellectually that free markets work best.

Mike Hammock writes:

If you haven't read Matt Ridley's The Red Queen, you should. I'm guessing Bryan would agree.

Stan Greer writes:

Troy Camplin, as the link I posted the other day, along with the internal links in that link, show exhaustively, adult male giraffes (the ones with the long necks) tend in most environments today to bend over to eat at least half of their food at levels other animals can reach.

Furthermore, there is no evidence there is insufficient food available at lower levels, even when there are lots of shorter animals around.

And if in the past, there was only enough food available at higher levels, how did young giraffes, who don't have long necks, survive to be adults?

Furthermore, anyone who observes giraffes know that there long necks make them easier, not harder, for lions and other predators to catch.

I am not denying natural selection ever explains changes in animals over time. I just think the giraffe is a very bad example.

Matt writes:

Sheep Nazi, thanks for the tip on the book.

There is a reason that agriculture should see resurgence in scholarly work. Underwater archeology has pushed agricultural development back another 3,000 years, and this puts the beginnings of agriculture back close to the interglacial epoch.

This epoch is that period in the glacial cycle where differential changes in CO2 production have compound effects on the top of the glacial cycle, and so human agriculture becomes a topic of interest when we discuss the failure of the last glacial cycle some 12,000 years ago.

Actually, I didn't say any of those things about giraffes. Obviously there is food at all levels in the savannas -- there are all sorts of animals of different sizes eating food at different levels. And if a giraffes finds some food it likes, it will certainly reach down to eat it. But that does not mean that there's not a benefit to having such a long neck. Don't get evolution backwards. People think that for giraffes to have long necks, they first needed long necks. That's not how it works (that is in fact a form of Lamarckian theory, disproved by Darwin's theories). As I said, there was a difference in developmental rates in the neck and legs of giraffes that resulted in the longer legs and neck. This likely spread through population genetics dynamics. However, if there was any benefit to having longer legs and necks, then that would have resulted in positive selection, accelerating the spread of this change. The ability (not necessity) to reach more leaves would have been quite beneficial. But having such a long neck does not mean that giraffes are restricted to leaves high up in trees -- it just means they have access.

Regarding size, please note that I did not say it was the length of the neck that helped prevent predation, but the overall size of the animal. Further, such long legs result in a very powerful kick that has broken the bones of enough lions to discourage giraffe attacks. The old and the young and the sick still face predation, of course, but you're not going to find too many lions bothering a healthy giraffe. This is well established through observation of wild giraffes and their interactions with predators.

WIth Darwinian theory, need does not drive change. The change occurs first and, if it is beneficial, it undergoes positive selection; if it is a neutral change, it spreads slowly through the population; if it is a negative change, it undergoes negative selection and will stay rare or be eliminated from the population.

Stan Greer writes:

Troy Camplin, I didn't say that orthodox Darwinists say giraffes got long necks because they wanted to eat leaves that were high up in trees.

But orthodox Darwinists do say that giraffes that had long necks due to mutations survived in far greater numbers, while short-necked "giraffes" basically disappeared, because they could eat more as a consequence of having long necks.

As I pointed out, there is no plausible evidence in favor of that contention. The fact that adult male giraffes (the only ones with the really long necks) sometimes eat leaves that are very high up in trees does not prove they need to do so, or benefit from doing so in a way that enhances survivability. I eat spaghetti sometimes because I like to and I can, but I doubt that means spaghetti eaters, as a group, are more likely to survive to adulthood and have offspring than nonspaghetti eaters. And the most important thing, evolutionarily speaking, is surviving to adulthood. And no giraffes have long necks until they're adults.

I also am not aware of any evidence that lions or other predators or in any way intimidated or deterred by the adult male giraffe's large size. Do you have any such evidence, or is it pure speculation?

I wonder if you actually read anything I wrote, because I already explained all of this. Twice. It could be a neutral mutation that spread through the population, or it could be a positively-selected mutation (suggested by the fact that they primarily eat acacia leaves, and acacias are generally large trees in Africa). But are allowable by contemporary Darwinist theory.

Females are only slightly shorter than males (1-2 ft. shorter), which has nothing to do with the arguments I made any more than young giraffes being obviously shorter (though tall enough to drink milk from mom) has anything to do with the arguments I made.

Just about everything I have read about giraffes has talked about the danger full-grown giraffes pose to lions. This isn't to say that no giraffes are ever eaten by any lions -- just that their size and kicking power are a deterrent to their being hunted. A kick from a giraffe can shatter a lion's skull, so lions naturally go for less dangerous prey when possible.

Stan Greer writes:

Troy Camplin, I certainly did read what you said before, but I don't think you read what I said, previously.

You do, however, make a couple of interesting points in the latest post, and I admit my knowledge on this subject is far from exhaustive. But frankly, I doubt yours is, either.

Perhaps you do know the answer to one question: Do young giraffes continue nursing until they reach their full height, or nearly so?

If so, you have at least one good point in your latest post. If not, then your point about nursing is quite irrelevant and doesn't address what I said.

The giraffes don't have to nurse until they are full grown, as there are trees of different sizes on the savannas. That doesn't mean that there's still not an advantage for a fully-grown giraffe to have the height (s)he has to be able to reach leaves others can't. Your requirements are contrarian for the sake of being contrarian to the point of being almost bizarre. Why is it so hard to understand that there might be an advantage in being able to reach leaves other animals can't reach, even if there are leaves lower down that can also be reached? It doesn't matter if there are leaves lower down that can be reached by giraffes and umpteen other animals -- being a little taller than the other animals and thus being able to reach a few more leaves can provide that slight advantage that keeps you around. And, really, all you need is one good drought or a fire that wipes out low-growing vegetation, and the slight advantage becomes more evident.

Giraffes, like many mammals, are social. They live in herds. They do not separate from their herds so easily. Say a fire goes through the savanna, burning off low-level leaves. All the other browsing animals go off to find leafy trees. The giraffes stay around, because they can reach higher-up leaves. But any short-necked giraffes would have a harder time eating, meaning some may die, others may be malnourished enough to have a harder time reproducing. The taller giraffes would be better nourished, being able to eat more, and would have a slight reproductive advantage, which gets translated quickly through the population (as per population genetics).

The fact that tall giraffes seem to have come about fairly rapidly suggests too that they underwent positive selection. The rapid transmission of a trait or gene through a population strongly suggests positive selection for it. Certainly not all traits have to undergo selection to come about, but at the least it can't be disadvantageous.

And while my knowledge of evolution certainly isn't exhaustive, I"m sure I learned more than a little something in that graduate level class on evolution I took when I was in grad school in biology.

Stan Greer writes:

So, small giraffes, after they've stopped nursing, aren't evolutionarily disadvantaged by not being able to eat from high trees, but tall giraffes who've grown up are evolutionarily advantaged by being able to do so.

I don't think I'm being "contrarian" in rejecting that preposterous argument. I give up.

Selection only occurs among sexually reproducing adults. If you lose a few immature giraffes one year, it doesn't matter all that much.

Scott Scheule writes:

That doesn't seem right. Certainly if you have young that tend to survive to adulthood, you'll be selected for. So it does matter if your immature giraffes are lost.

Incidentally, most of the information I can find online seems to support Stan's view.

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