Distributed Attention

About 75,000 years ago the Homo genus reached its greatest crisis. The erectus species in Asia went extinct, the sapiens in Africa went through a bottleneck in which only a few thousand managed to survive, and the neanderthalensis branch in Europe began to collapse, finally dying out altogether when the last bastion of survivors, in Gibraltar, gave way 28,000 years ago. An erectus line may have held out until 15,000 years ago by miniaturizing itself on the island of Flores in Indonesia. Meanwhile, by the time of those final flickers in Gibraltar and Flores, Homo sapiens had recovered well enough to have spread across Asia, Africa, Australia, and Europe. They were poised to enter the American continents as well.

I’ve been thinking about these extinctions, and one other matter, since going over Nina Jablonski’s presentation to  the American Association of Science’s annual meeting last weekend. (Summarized here.) The one other matter I've been pondering is something Jablonski pointed out: survival of the crisis was achieved by slightly shrinking the brain and body. A two million year trend was halted. Had we gotten as smart as we could?

We had probably gotten as smart as we needed any individual to be. From here on out, it's the community that gets wiser.

Jablonski’s presentation did not say much about the Homo communities and nothing about the role of speech in these survivals and extinctions. She did include one slide about culture and human life histories, noting that humans have undertaken the

collective care of infants, so that the attentions of females of reproductive age do not have to be focused solely on the upbringing of their own single infants.

It is not just that our brains have been getting larger and smarter (See: Smarter is Fitter). Our attention (note that Jablonski refers to the attentions of females)  has become “collective,” or to use the modern, computer-oriented term, distributed, and the central tool of distributed attention has been speech.

The benefits of distributed operations are easily demonstrated, but their development has to work within the severe restraints of evolutionary possibilities. A major constraint has been “selfishness,” the requirement that any surviving gene prospers more than its competitors. I have discussed this issue before on this blog, but it is worth repeating because it is central to the problem of speech origins.

It is very easy to think up scenarios in which speaking to one another helps everybody in the group, but it is very hard to find ways in which the rise of speech might be supported by a system of competitive genes in which everybody is looking after number one.

• If it is in Henry’s interest to  learn what Peter knows, why is it in Peter’s interest to tell Henry what he knows?
• Peter could benefit from Henry’s support, but why should Henry listen to what Peter has to say?

Questions like these are so basic they sound trivial or even cynical, but without answers the constraints of evolutionary competition cannot be surmounted.

Yet, obviously, in our case they were surmounted. Jablonski’s presentation on extinction events reminds us that the bipedal ape was a very iffy experiment. Boldly going where no primate has gone before tends eventually to lead into a dead end.

The solution we hit upon was made possible by a new form of communication that enabled a distribution of attention: speech. We got around the competitive restraints by first distributing emotional attention, then meaningful attention, and finally ceremonial attention. These developments got us through the dangers of the extinctions that were wiping out our evolutionary cousins.

Surviving the first extinction appears to have entailed giving up one of the ape’s greatest luxuries, long spacing between childbirth. Jablonski presented a table showing gibbons and orangutans both having longer average intervals between births than humans, and this blog has had an extensive discussion of work by John Locke and Barry Bogin on the way humans have shortened birth intervals by early weaning and introducing a childhood period of dependence on “baby food” until the first permanent teeth appeared. (See: The Long Parenthood) This tactic spared us the doom of the Australopithecines but added the burden of tending more than one utterly dependent youngster at a time.

The normal competitive solution for this kind of added burden would be to evolve a super-mom able to handle all this by herself. But as mothers continue to say, “I’ve only got two hands,” and “There are only 24 hours in a day.” Apparently, more competition wasn’t good enough, so instead, we developed community care. Children entertain one another during childhood and females as a group collectively attend to the children. Apparently it was possible to reduce Darwinian selfishness through the development of emotional communications—babbling, music, and possibly other forms of sound making.

Jablonski is a promoter of the idea that the survivors of the first hominid extinction were sweaty, long-range foragers. It makes sense, but the African savannas are vast. I have personally driven for hours across them without finding anything of note. By foot, that would have been a couple of days of fruitless travel. It requires more than an ability to cover ground to survive out there; you have to cover the ground wisely.

Again, the normal competitive solution would be to develop individual wisdom, but that is constrained by the high costs of big brains. A different approach is suggested by folk wisdom, “Two heads are better than one.” Once emotional bonds were formed, meaningful communication of the Hey,-over-here and Wait-up sorts become invaluable. Your Homo group could spread out and examine the land for clues until somebody found something. A competitive fellow might keep the news to himself, but one with emotional ties would direct his companions’ attention to the discovery. For a million years the Homo erectus/ergaster line was probably improving its ability to distribute attention through a group by developing meaningful speech, changing the blacks of the eyes to whites, etc.

The success of distributed, meaningful attention enabled hominids to spread well beyond the tropics, and yet ultimately that answer was not enough. There was that second great extinction, the crisis of 75,000 years ago, deep in the heart of the last Ice Age, where nobody seemed to have a solution. It might appear that Homo sapiens was just lucky, passing through a bottleneck when they might just as easily have expired like the erectus line. But Homo sapiens didn’t just survive a difficult time; they prospered while the other groups of survivors were disappearing bit by bit. And remember, some of those shrinking groups had bigger brains than our own ancestors.

Here at last we have some specific archaeological evidence about what was going on. The sapiens line had developed ceremonial communication, using drawings, sculpture, body paint, and (surely) speech to hold their groups together on the basis of some new ceremonial identity. At this point community-based altruism becomes possible; people understand their personal interests in terms of community interests. We get the distributed attention that earlier Homo had enjoyed, plus a commitment to the group that goes beyond emotional bonding. At this point, self-sacrifice becomes a possibility and the human line has really gotten beyond the classic Darwinian constraints of competitive genes. It might seem impossible, except that we are here and the other Homo species are not. With a committed, distributed attention we could even shrink our brains a bit, put less stress on the environment, and thrive. Since then, it has been communities that have been growing increasingly knowledgeable. The last real Renaissance Man, somebody who literally knew everything that anybody else in the group knew, was probably a Neanderthal. By then a sapiens group already had by then somebody who knew the local plants best, somebody else who remembered the ceremonial traditions, and still somebody else who knew all about midwifery.

By the way, there was another extinction that Jablonski mentioned in passing. It did not concern the Homo line directly, but about 10,000 years ago there was another mass extinction. With the melting of the Ice Age glaciers, the Pleistocene Epoch came to an end and with it went many species that had been well adapted to those rough times. But Homo sapiens was not among the losers. We did fine, although I notice that at this time many of our ancestors gave up their millions-of-years-old history of nomadic living to become settled farmers, iron workers, and traders. Oh, and once again we expanded our communications repertoire, adding written language to the mix.

Comments

[John Blake]

Some 72,000 - 75,000 years ago, the Toba Eruption in Indonesia left a crater eighty miles long by fifty miles wide. Akin to a moderate meteor-strike, this geophysical catastrophe all but extinguished modern-day primates (evolving "Homo sapiens"). We need not adduce any fancy bio-evolutionary mechanisms: All but a few hundred breeding pairs survived, huddled behind the Central African massif crowned by Kilimanjaro on the East.

This near-eradication accounts for the human species' extraordinary genetic homogeneity: From a minuscule basis, "genetic drift" over a mere 75,000 years has necessarily been minimal. More interesting, though mankind's racial diversity may be genetically marginal, it seems that qualitative aspects outweigh mere quantitative factors.

Call "qualitative" what you will, it's not just Neanderthals and perhaps related strains that suffered in relation to Homo's rapid divergence "out of Africa", filling ecological and evolutionary niches vacated in Toba's great die-off. Above the Northern Mediterranean, more challenging environments than African savannahs apparently fostered aggressive socio-cultural, even intellectual development. Fuss and grump you may, but the historical record stands. Migration left Africa behind.

Academics unaware of determining factors beyond their blinkered specialities wax over-confident in
predictable ways. Let's just say, they ignore larger realities at peril.

The current contretemps over "global warming" is analogous to 60-year controversies attending Alfred Wegener's hypothesis of Continental Drift. Assuming continental land-masses were identical to ocean bottoms, geophysicists pooh-poohed Wegener
until the mid-1960s, when deep-ocean probes resolved that Africa had indeed split off from South America. In brief, today's missing element is deep-ocean volcanism, dating from at least 1850 but discovered worldwide (in Arctic, Indian Ocean, Pacific Rim) only since 2001.

Ocean warming drives evaporation, an air-conditioning (cooling) effect that occasions heavy atmospheric precipitation-- cold rains in summer, massive snowfalls in winter. As a volcanic effect, surging CO2 levels aggravate cooling by pyramiding warm-water evaporation. Glaciers do not move south: They land on our heads with 90-foot snowfalls, whose albedo then shifts warm-water currents like the Gulf Stream hundreds of miles south.

Bingo-- Ice Age, persisting 120,000 years. Over the last 10-million years, interglacials have lasted 12,000 years on average. We are now 12,500 years past the Younger Dryas... and there are other factors, intra-solar and cyclical from 1313 to 2113 which do not augur well.

Where once the Toba Eruption defined humanity's genetic makeup, we now face a perfectly standard Ice Age. If not our children, our grandchildren may face extinction as populations war for climate-zones still cultivable. But we ourselves will be dead, and the World thereby a better place. Tamam!
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BLOGGER: Thanks for this post. It feels like a real contribution of the sort I would love to see as a regular part of this blog.

[John]

http://www.bradshawfoundation.com/journey/

Interesting timeline/migration model.

There can be no doubt that the Toba eruption was a massive event that must have had a massive impact.