By which I mean multi-step causal chains that are part of a complex plan – something intended by some individual or group. In the strong form, one for which the initial push is sufficient, so that the ball ends up in the right place without any continuing guidance. In practice, we’re talking patterns like that in human affairs.
They don’t exist. And when someone says ” Group X must have intended Y”, invoking that kind of logic – he’s an idiot. Pay him no never mind.
I don’t think the story is perfectly clear right now. But suppose it becomes clear. Suppose that we find that Covid-19 was ( for sure) the accidental product of virologists working in a Wuhan lab, funded by the US government.
I’ve been reading Thin on the Ground, a book by Stephen Churchill. One of his ideas is based on the fact some predator species are dominant over others and get the lion’s share (cough, cough) of the kills. Lions frequently steal carcasses from hyenas, while everyone steals from cheetahs and wild dogs, etc.
There is good evidence ( stable isotope data) that Neanderthals were highly carnivorous, and that they used thrusting spears, which are effective but not as generally useful as atlatls – standoff weapons. Churchill suspects that with their thrusting spears tech, Neanderthals were _not_ the top dogs of the predator guild, and that they may have been dominated by cave lions and scimitar cats, while having approximately equal status with hyenas. In practice, this would mean that Neanderthals often lost kills to high-ranked carnivores such as cave lions. The majority of calories from animal kills would go to higher-ranked carnivores ( not to Neanderthals) . Neanderthal population size would be limited, and some environments ( like open plains, where kills are highly visible) might be effectively closed to them.
Neanderthals don’t seem to take much advantage of the Atlantic salmon runs – maybe da Bears didn’t let them.
We think of Man as #1, and generally that’s the case nowadays, but it wasn’t always true.
So imagine that the Predecessors, the population that left those footprints at White Sands, didn’t have the atlatl. They may have arrived as fishermen, and may have been gradually re-inventing and improving their hunting techniques. They had to compete with short-faced bears, sabertooth tigers, the American lion, dire wolves, the American cheetah, grizzly bears, and wolves. Their diet was not as limited as that of the Neanderthals – North America was warming and plant foods were available – but they may have been dominated by some of the larger predators. if so, their cut of the herbivores may have been limited, they may have been limited to certain kinds of terrain, etc. They may have been thin on the ground, like Neanderthals.
Third example: we know that modern humans arrived even earlier in Australia/New Guinea ( then joined as Sahul), and those humans _were_ ecologically dominant, even though they did _not have atlatls ( until fairly recently), as far as we know. They became common enough to leave noticeable numbers of artifacts and skeletons, and they drove most of the Australian megafauna to extinction.
Why would human domination be easy in Australia and hard for Predecessors in the Americas?
I would guess because the dominant predators of Sahul were reptiles and marsupials.
The problem with the idea of an early, pre-Amerindian settlement of the Americas is that ( by hypothesis, and some evidence ) it succeeded, but ( from known evidence) it just barely succeeded, at best. Think like an epidemiologist ( they’re not all stupid ) – once humans managed to get past the ice, they must have had a growth factor greater than 1.0 per generation – but it seems that it can’t have been a lot larger than that, because if they had averaged, say, 3 surviving kids per generation ( r = 1.5) , their population would have exploded, filling up all the habitable territories south of the glaciers in less than 2000 years.
(1.5)^40 multiplies the original population by a factor greater than ten million !
A saturated hunter-gatherer population inhabiting millions of square miles leaves a fair number of artifacts and skeletons per millennium – but we haven’t found much. We have, so far, found no skeletons that old. I don’t think we have a lot of totally convincing artifacts, although I’m no expert at distinguishing artifacts from geofacts. ( But these were modern humans – how crude do we expect their artifacts to be?)
For-sure footprints we’ve got, and intriguing genetic data.
A priori, I would expect hunter-gatherers entering uninhabited America to have done pretty well, and have high population growth rates, especially after they become more familiar with the local ecology. There is good reason to think that early Amerindians did: Bayesian skyline analysis of their mtDNA indicates fast population growth. They were expert hunters before they ever arrived, and once they got rolling, they seem to have wiped out the megafauna quite rapidly.
But the Precursors do not seem to have become numerous, and did not cause a wave of extinctions ( as far as I know. check giant turtles.). What might have limited their biological success?
Maybe they didn’t have atlatls. The Amerindians certainly did.
Maybe they arrived as fishermen and didn’t have many hunting skills. Those could have been developed, but not instantaneously. An analogy: early Amerindians visited some West Coast islands and must have had boats. But after they crossed the continent and reached the Gulf of Mexico, they had lost that technology and took several thousand years to re-develop it and settle the Caribbean. Along this line, coastal fishing settlements back near the Glacial Maximum would all be under water today.
Maybe they fought among themselves to an unusual degree. I don’t really believe in this, am just throwing out notions.
Maybe their technology and skills set only worked in a limited set of situations, so that they could only successfully colonize certain niches. Neanderthals, for example, don’t seem to have flourished in plains, but instead in hilly country. On the other hand, we don’t tend to think of modern human having such limitations.
One can imagine some kind of infectious disease that made large areas uninhabitable. With the low human population density, most likely a zoonosis, perhaps carried by some component of the megafauna – which would also explain why it disappeared.
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.
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.