Footprints in the Sands of Time

The fossil footprints around an ancient lake in White Sands have been known for some time, but now we have what look to be perfectly respectable C-14 dates. They’re about 22 thousand years old, close to the Last Glacial maximum (LGM) and, as such clearly predate all existing evidence of human settlement of the New World (south of the glaciers, anyhow).

There were already hints: Amerindian populations in South America, mainly in Amazonia, carry a trace of a different genetic heritage. The existing population closest to that trace are the inhabitants of the Andaman Islands, between India and Burma. Other populations such as Australian Aborigines and the inhabitants of New Guinea are also close. There is reason to believe that, until a few thousand years ago, all of Southeast Asia (including the islands) was occupied by related populations, known as Australo-Melanesians.

Here’s the key insight: the fact that the Andaman-like genetic trace is found in Amazonian Amerindians, but not in North America, suggests that it was picked up from a pre-existing population as the Amerindians expanded into South America. There are other possible scenarios, but it is hard to fit them with certain known facts. For example, we have ancient DNA from a Clovis kid, which is genetically close to modern Amerindians in South America, but does not contain this Andamanese-like trace. Hard to make this scenario work.

This implies that there was an earlier, less-successful colonization of the New World, one that preceded the Amerindians. One could have predicted this, and I did.

North America looked something like this in those days:

Note that crossing by boat would have been difficult at this time, assuming that settlers closely followed the coast. There is a long stretch of icebound coast before you reach somewhere habitable. The LGM was perhaps the most difficult time for a population to reach North America from Asia, so you have to suspect that they had crossed even earlier.

I say “less successful” because this population left very little sign, compared to the later Clovis culture. We find many artifacts and some skeletons from the early Amerindians, but very little from this (hypothetical) earlier population: in part this might be because their artifacts are harder to recognize ( because primitive) , but you have to think that their population density was considerably lower.

They may have done better in Brazil, because its climate was more favorable for hunter-gatherers than most places were back in the dreadful LGM.

One of the interesting differences between this somewhat hypothetical early population and Amerindians is that they seem to have been far less competent hunters. By the time of Clovis, Amerindians had atlatls and could apparently kill any animal, no matter how large. Ecologically dominant. In fact, they seem to have driven almost all of the megafauna in North and South America into extinction over a fairly short period of time.

This [hypothetical] earlier population may not have had atlatls simply because they hadn’t been invented yet: the earliest known example is about 18,000 years old. Considering that they may have entered North America some time well _before_ the LGM, this seems likely.

It may be that the alternative to being ‘ecologically dominant’ in the Americas was not very pleasant. The Amerindians could make a living hunting megafauna, and probably could deal effectively with the big predators sustained by those megafauna – at minimum, they were tough enough to make those predators think twice. After the extinction of the megafauna, most of those predators disappeared. This means that every other strategy of making a living – hunting lesser game, fishing, gathering plant foods – could be pursued without much risk. The whole landscape was theirs – the only thing they had to fear was other Amerindians.

For our hypothetical Precursors, this may not have been the case. Predators may have excluded them from much of the landscape, reducing their access to resources, which may not have been very abundant anyhow in the most severe part of the Ice Age.

It is safe to say that they didn’t leave a lot of skeletal fossils, since so far we haven’t found a single one. At the same time, any skeletal sample with useable DNA would be very valuable: as with the key Denisovan sample, where we have learned much about a whole separate branch of humanity from part of a little finger!

We can hope for luck finding skeletal fossils, but there may be another, more fruitful approach: looking aDNA in sediments in ancient sites. People have successfully retrieved ancient DNA from Neanderthal sites, and we may hope to do the same for pre-Clovis sites in the Americas. People ( other than James Bond) only die once, but they take a crap many times before their deaths. This approach might let us acquire genetic evidence from very early cultures, cultures with low population size, perhaps essentially failed colonizations or short-term explorations.

You Have Been in Afghanistan, I Perceive

The African Queens

Honeybees are an Old World species and likely originated in Africa. In order to succeed in places with cold winters, like Europe, they had to develop new adaptations. Mainly behavioral adaptations: they retreat to their hives and form a winter cluster. The workers and the queen crowd together tightly, with the queen at the center, and the workers shaking and shivering. The cluster moves around to reach reserves of honey.

The winter generation is different from summer bees: a bit plumper, and they have a several-fold longer lifespan to make it through the winter. (queens have an even longer lifespan – several years)

Their strategy means that they have to store enough honey to feed the hive over the winter.

Honeybees were introduced to the New World by European settlers and did well, often swarming many times a summer.

They don’t seem to have done as well in tropical areas of the New World.

In the 1950s, a mad scientist decided to cross some African bees with European strains in the hope of making Brazilian bees busier. However, a number of African-strain queens escaped.

The resulting hybrids – Africanized bees – were successful, mainly because they invested in more bees, rather than saving honey for the nonexistent Brazilian winter.

This had consequences. Africanized-bees are probably more economically useful in those warm climates: they produce less honey, but honey production is not nearly as important as crop pollination. More bees, more pollination.

Eventually they spread all over the tropical and subtropical parts of the New World, limited only by cold winters.

The disadvantage is that Africanized bees are very aggressive, to the point of being dangerous. They can sting people to death: they are responsible for something like 1000 deaths since their introduction. Thus, ‘killer bees’.

I’ve known this story for a long time, but recently ran into one more interesting wrinkle. Bees can learn. They can associate the location of a favorable site with various characteristics and can remember profitable sites from day to day. They can learn to associate an originally neutral scent with a sugar reward. Within a honeybee population, there is genetic variation in learning abilities.

Which raises the natural questions: are bee subspecies equal in their ability to learn?

In this study, the authors hypothesized that Africanized bees might be spreading because they had greater cognitive capabilities than the European honeybees: brains rule OK!

There are certainly examples of this: humans displace chimps because we’re smarter, and it seems likely that placental mammals ( like cats ) have a cognitive advantage over native Australian marsupials.

But, as it turns out, European honeybees perform significantly better in a learning assay that Africanized honeybees do. I think that simply skipping an expensive behavior that has no payoff in a warm climate ( saving up lots of honey) is enough to explain most of the observed killer bee fitness advantage.

I would guess that the selective pressure for better learning in European bees is due to the payoff for remembering prime nectar and honey locations over the several months of winter. Africanized bees don’t have that kind of long pause in foraging, have less need to remember such patterns for long periods. Perhaps.

Sex is a spectrum

Theodosius ruled ok!

The Olympics was never a very good idea.

Son of Low-Hanging Fruit (again)

In yet another example of  long-delayed discovery, forms of high-altitude lightning were observed for at least a century before becoming officially real (as opposed to really real).

Some thunderstorms manage to generate blue jets shooting out of their thunderheads, or  glowing red rings and associated tentacles around 70 kilometers up.   C T R Wilson predicted this long ago, back in the 1920s.  He had a simple model that gets you started.

You see, you can think of the thunderstorm, after a ground discharge,  as a vertical dipole. Its electrical field drops as the cube of altitude.  The threshold voltage for atmospheric breakdown is proportional to pressure, while pressure drops exponentially with altitude: and as everyone knows, a negative exponential drops faster than any power.

The curves must cross.   Electrical breakdown occurs.  Weird lightning, way above the clouds.

As I said, people reported sprites at least a hundred years ago, and they have probably been observed occasionally since the dawn of time. However, they’re far easier to see if you’re above the clouds – pilots often do.

Pilots also learned not to talk about it, because nobody listened.   Military and commercial pilots have to pass periodic medical exams known as ‘flight physicals’,  and there was a suspicion that reporting glowing red cephalopods in the sky might interfere with that.  Generally, you had to see the things that were officially real (whether they were really real or not), and only those things.

Sprites became real when someone recorded one by accident on a fast camera in 1989.  Since then it’s turned into a real subject, full of strangeness: turns out that thunderstorms  sometimes generate gamma-rays and even antimatter.

Presumably we’ve gotten over all that ignoring your lying eyes stuff by now.

Flee at Once ! All is Discovered !

In the last few years, law enforcement has begun to cash in on modern genetic technology in a new and more powerful way, one that works on perps that have been careful enough to avoid being genotyped.

The perp’s DNA sample is matched against a large database of genome sequences, and if a moderately long subsequence is identical-by-descent, it’s clear that the perp and the matching person in the database share fairly recent common ancestry. The degree of sharing shows, approximately, how recent that common ancestry is.

This has been done for some time with close relatives, which share up to 50% of their DNA. But by now, enough people have been genotyped that there’s a pretty good chance that the typical perp ( of European ancestry) has some moderately distant match in the database: say, a 3rd cousin. We can now detect those matches. A few such matches tells us that the unknown perp is one of the descendants of an ancestor a few generations back – so we now only have to examine a very limited pool of potential perps, perhaps a few hundred instead of tens of millions! After excluding individuals of the wrong sex, impossible ages, deceased, etc finding the real killer often becomes quite practical.

In particular, enough people have been genotyped and have uploaded their info to a genetic genealogy site to allow this. I said of European descent: genotyping and interest in genealogy have not as yet been widespread enough among African-Americans to allow this approach , but that will come, probably fairly soon.

What this means, to a pretty good approximation, is that law enforcement is soon going be able to identify the perp in all cases where DNA evidence is available. Decades of unsolved rapes, assaults, and murders will be cleared up – in as little as a couple of years, if we make a serious effort.

Exceptions? DNA from your evil twin, and DNA from truly obscure groups with no representatives in the US. People will write murder mysteries featuring Andaman Islanders -they’ll have to.

We will not find that all or most prominent people have a criminal past ( I think) – but quite a few will, undoubtedly including people you would never have guessed. It will even include people that I never suspected. Successful guys that rarely think about that perfectly understandable mistake that happened ever so many years ago will suddenly find themselves wearing orange jumpsuits. They’ll wish they had converted their holdings into Krugerrands or bitcoin, vamoosed to Chad or Yemen, but it will be too late.

Unless they act now.

Kurgan

If we combine genetic genealogy and the new method of determining identity-by-descent in ancient DNA, we could, and should,

search for immortals.

Calling a deer a deer

We all know that most people are pretty good at calling a deer a horse – pretending that the Emperor really is wearing uncommonly fine clothes that are only invisible to stupid or unfit people, etc.

Most of the time, the penalty for calling a deer a deer is not as drastic as that exacted by Zhao Gao. Most of the people saying instantly falsifiable things about current issues are not doing it because someone is holding a gun to their head. Sometimes negative career consequences are a possibility, more often social penalties, but it seems to me that most people want to go along – outside threats are not the biggest drivers.

Now we all know that going along with horseshit can be a bad thing for society as a whole, sometimes even at the individual level. It is good for society to avoid marching off a cliff, and that is also good at the individual level, even if everyone else is doing so.

But being right when nearly everyone else is wrong does not necessarily confer a net benefit.

Sure, you avoid walking on air – but the penalty for conformity is not always that dramatic, while the penalties for _nonconformity_ are almost always there. They happen even if you’re proved right – maybe especially if you’re proved right.

Still, there are some people that prefer the truth to the trend and have enough mental horsepower to get there fairly often.

The question is, is this a bug or a feature? Is it bad for fitness, or is it some kind of minority genetic strategy? Sure, it has some social utility, but that doesn’t pay the genetic bills.

Kolmogorov’s options

A while ago, Scott Aaronson wrote about Kolmogorov’s way of dealing with life in a Stalinist paradise. He mentions how Kolmogorov testified against his former mentor Luzin. It is suggested that Kolmogorov was blackmailed into doing this by the secret police, who threatened to reveal Kolmogorov’s homosexuality.

But that’s silly. It is based on the assumption that Stalin’s agents needed a reason to put you in the jug, send you to Siberia, or kill you. If you kept your nose clean, obeyed the written and unwritten rules, nothing bad could happen to you! Because that would be wrong !

The firmament of the Soviet Union during the Great Purge was studded with dead stars. No one was safe, no one was innocent. Old Bolshies, creative artists, four-star generals, farmers with a cow, ex-heads of the Cheka, personal friends of Stalin serving in the Politburo – nothing made you immune.

Supreme talent in a profession with military applications gave better-than-average protection: there were some scientists that, as far as we know, never informed on anyone. I’ve never heard that Kapitsa did.

That was probably more the case after the Bomb, when the survival and success of the state hinged on nuclear physics, and they really had to put up with people like Sakharov.

Kolmogorov was a hell of a mathematician, but not a particularly admirable man.