Tag Archives: Biology

Ancient Hobbits

It remains one of the greatest human fossil discoveries of all time. The bones of a race of tiny primitive people, who used stone tools to hunt pony-sized elephants and battle huge Komodo dragons, were discovered on the Indonesian island of Flores in 2004. …

According to a growing number of scientists, Homo floresiensis is probably a direct descendant of some of the first apemen to evolve on the African savannah three million years ago. …  It sounds improbable but the basic physical similarity between the two species is striking. … Analysis of Lucy’s skeleton shows it has great similarities with the bones of H. floresiensis, although her species died out millions of years ago while the hobbits hung on in Flores until about 17,000 years ago. …

The crucial point about this interpretation is that it explains why the Flores people had such minuscule proportions. … In research that provides further support for this idea, scientists have recently dated some stone tools on Flores as being around 1.1 million years old, far older than had been previously supposed. … He has now uncovered stone tools on nearby Sulawesi. These could be almost two million years old.

More here.  HT Tyler.

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Animal Smoking Studies

Some seem to think experiments show smoking causes cancer in animals.  Not so, for mice or rats:

I review the results of a representative selection of chronic inhalation studies with rats and mice exposed to mainstream cigarette smoke. … Smoke-induced epithelial hypertrophy, hyperplasia, and squamous metaplasia were reported in the conducting airways in most of the studies, along with increased numbers of intra-alveolar macrophages that were occasionally associated with alveolar metaplasia. Lung adenomas and adenocarcinomas were reported in only a few of the studies. No statistically significant increase in the incidence of malignant lung tumors was seen. …

The 14 studies reviewed … [showed] significant increases in the numbers of malignant tumors were not produced in the respiratory tracts of rats or mice exposed chronically by inhalation to cigarette smoke.  The studies clearly involved the inhalation of very large amounts of smoke (usually from unfiltered, high-tar cigarettes) …  The results of this work clearly indicate that maximal amounts of smoke were inhaled into the lungs of the animals (blood COHb concentrations very close to those associated with lethality) daily for up to 2 yr with no carcinogenic effect noted.

Nor for hamsters, dogs, or primates:

This paper makes an identical evaluation as before, but, restricting the species being evaluated to representative studies of smoke-exposed hamsters, dogs (both by tracheostomy and by direct inhalation), and nonhuman primates. As was seen previously, no statistically significant increase in the incidence of malignant tumors of the respiratory tract was found in any of the 3 species, even though very long exposures and high doses of smoke were used.

Now the number of animals in these studies is a few thousand at most, and their duration is less than decades, but experimenters did have complete control over making animals smoke heavily.  Yes this review author works for a tobacco firm, but his papers seem professional.

Searching for “animal smoking experiments,” I found many sources admitting we haven’t found much evidence smoking hurts animals, and none saying the opposite.  Here is a ’97 Scientific American article “Animal Research is Wasteful and Misleading”: Continue reading "Animal Smoking Studies" »

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Monogamy Is Human

It easier to maintain pair bonding in larger primate social groups if males can’t easily tell when females are fertile.  In turn, monogamy makes it easier to keep the peace in larger groups.  And since folks in large groups have more uses for big brains, and more resources to pay for them, monogamous social apes should have bigger brains.  So monogamy encouraged by hidden female fertility may have been the key to humans succeeding far beyond other apes.

Why might we think this?  Chimps are humans’ closest living relatives, splitting apart 5-7 million years ago.  The Ardipithecus ramidus proto-humans of 4.4 million years ago were bipeds with a broad diet in woods and grasslands, and with a brain

about the same size as a modern bonobo or female common chimpanzee brain … The less pronounced nature of [their] upper canine teeth … has been used to suggest that the last common ancestor of homonids and African apes was characterized by relatively little aggression between males and between groups.

A recent Science article persuasively elaborated this argument:

Elimination of the [upper canine teeth] in hominids is unique among all higher primates and occurred long before Australopithecus. … Available evidence now suggests [it] was, as is theoretically most likely, a social adaptation … consistent with a strategy of increasingly targeted provisioning. …. Males would benefit from enhanced male-to-male cooperation …. Foraging could be achieved most productively by cooperative male patrols … Provisioning would reduce female-to-female competition … and would improve (or maintain) social cohesion. …

A large brain is not our most unique characteristic. … The combination of [upper canine teeth] elimination, habitual bipedality, and reproductive crypsis (each in itself an extreme rarity) is unique among all known mammals. Conversely, simple brain enlargement is readily explicable in myriad ways.

They plausibly suggest that these three key uniquely human features appeared together over 4 million years ago, leading over time to our uniquely large human social groups and brains, and all else they imply.

If monogamy is this essential to human success, that does make me a bit more concerned about current trends away from monogamy.  Of course hunter-gatherer monogamy may only have been for 4+ year periods, and we are in some ways moving more toward that.  But still, it gives me pause.

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Humans Are Evolving

The team studied 2238 women who had passed menopause and so completed their reproductive lives. For this group, Stearns’s team tested whether a woman’s height, weight, blood pressure, cholesterol or other traits correlated with the number of children she had borne. They controlled for changes due to social and cultural factors to calculate how strongly natural selection is shaping these traits.

Quite a lot, it turns out. Shorter, heavier women tended to have more children, on average, than taller, lighter ones. Women with lower blood pressure and lower cholesterol levels likewise reared more children, and – not surprisingly – so did women who had their first child at a younger age or who entered menopause later. Strikingly, these traits were passed on to their daughters, who in turn also had more children.

If these trends continue for 10 generations, Stearns calculates, the average woman in 2409 will be 2 centimetres shorter and 1 kilogram heavier than she is today. She will bear her first child about 5 months earlier and enter menopause 10 months later.

More here. And this is just for the few parameters tested in this study; no doubt many more features are evolving as well.

Our culture respects taller thinner women who wait longer before having kids, but in fact we are evolving short heavy women who have kids earlier.  Shades of Idiocracy – in many ways we are evolving to become less of what we now respect.

In principle humans could implement strong central regulations to ensure that they evolved to become the sort of creatures they respect, at least regarding a few features of regulatory focus.  But it is far from clear that we are willing, or even able, to achieve this.  And it is far from clear to me that we would be better off achieving such far ideals. Perhaps short plump early moms are happier, after all.

Of course I expect that within a century the main dynamic will be even faster robot evolution, but the same principle will apply – without strong central coordination they are unlikely to evolve to become what we or they most respect.

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Bad News On Human Extinction

Disasters that destroy all but a thousand humans are more likely than disasters that destroy all but a hundred humans.  So this news says human extinction is more likely than we thought:

Conservation biologists may be deluding themselves. An analysis of the minimum number of individuals needed for a species to survive in the long term has found that current conservation practices underestimate the risk of extinction by not fully allowing for the dangers posed by the loss of genetic diversity. If correct, it means the number of individuals in endangered species are being allowed to dwindle too far.

Lochran Traill at the University of Adelaide, Australia, and colleagues found that for thousands of species the minimum viable population size (MVP) – where a species has a 90 per cent chance of surviving the next 100 years – comes in at thousands rather than hundreds of individuals. Many biologists, Traill says, work with lower numbers and so allow unacceptably high extinction risks.

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Height Puzzle

Among adults of industrial nations, growth stunting … is associated with worse indicators of adult well-being (e.g., income). … Here we … [consider] the Tsimane’, a foraging-farming society of native Amazonians in Bolivia. Subjects included 248 women and 255 men measured annually during five consecutive years (2002-2006). Nine outcomes (wealth, monetary income, illness, access to credit, mirth, schooling, math skills, plant knowledge, forest clearance) were regressed separately against a stunting dummy variable and a wide range of control variables. We found no significant association between any of the indicators of own well-being and adult stunting. …

In South Africa, a comparison of short-for-age “Cape Coloured” children showed that those growing up under poorer socioeconomic conditions had lower body weight, height, and physical performance than the more advantaged children … Among adults of industrial nations, standing physical stature is positively associated with many indicators of own adult well-being, such as occupation, monetary income, wages, IQ, longevity, and good health.

More here.

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Nature is Doomed

Long ago humans pioneered some very powerful innovations, innovations that have allowed us to grow in capability much faster than the rest of nature.  As humans grew more capable, we learned to live in more kinds of places, and to use more of the plants and animals in each place.  We didn’t always destroy non-human living nature – sometimes we converted it to farms, pets, or parks.  But we only left nature alone when we couldn’t figure out how to make use of it, or of what it used.  Our expanded use of nature has left less for other species, often leading to their extinction.

This trend has continued in recent times: as we learn more ways to use nature, we use nature more.  There has been, however, one notable exception: rising wages over the last few hundred years have made us abandon some old practices.  For example, during the depression my grandparents farmed marginal land in Kentucky that is now forest.  We still know how to farm the land, and with free immigration it would still be farmed, but as it is labor is too expensive for farming.

This reprieve won’t last.  Wages have risen because economic growth rates have outpaced feasible rates of growing well-trained people.  But current growth rates simply cannot continue at familiar levels for ten thousand more years.  We’ll eventually learn everything worth knowing about how to arrange atoms, and growth in available atoms will be limited by the speed of light.  So over this timescale growth rates simply must fall below feasible population growth rates.  (I actually expect a new brain emulation tech to allow very fast population growth in a century or two, but this is tangential to my argument here.)

With familiar competitive habits, this growth rate change implies falling wages for intelligent labor, canceling nature’s recent high-wage reprieve.  So if we continue to use all the nature our abilities allow, abilities growing much faster than nature’s abilities to resist us, within ten thousand years at most (and more likely a few centuries) we’ll use pretty much all of nature, with only farms, pets and (economically) small parks remaining.  If we keep growing competitively, nature is doomed.

Of course we’ll still need some functioning ecosystems to support farming a while longer, until we learn how to make food without farms, or bodies using simpler fuels.  Hopefully we’ll assimilate most innovations worth digging out of nature, and deep underground single cell life will probably last the longest.  But these may be cold comfort to most nature lovers.

Yes, nature would be saved if we destroy ourselves without destroying nature in the process, but hopefully we’ll avoid this scenario.  We might also somehow coordinate to prevent competitive growth.  For example, we might empower a world government to protect nature, prevent innovation, or prevent population growth.  But I honestly see little prospect of this.  We now live in a very competitive world, and even governments mainly just redirect competition, toward controlling those governments.

We like nature, but aren’t really willing to pay the price it would take to save most of it.  Nature than cannot survive as farms, pets, or small parks, is doomed.

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The Dark Side of Cooperation

Cooperation is a popular topic these days.  For example, see this Science review article and this Nature book review of de Waal’s The Age of Empathy:

A repeated foil throughout is Gordon Gekko, from the 1987 movie Wall Street, who reiterates in various forms the basic credo that “greed is good”. … [de Waal's] main political message is that we should not continue to harp on about evolution justifying only the selfish side of human nature, although of course that exists. He urges that we must also capitalize on the empathetic and cooperative attitudes that evolution has equipped us with, writing: “A society that ignores these tendencies can’t be optimal”.

Here is a New Scientist book review:

Given all that we know about empathy in animals, why do so many persist in seeing ours as a dog-eat-dog world? De Waal chalks it up to what he calls “macho origin myths”, which insist that “our species has been waging war for as long as it has been around”. But humans have shown empathy for as long as we’ve been around too.

Many stories discuss recent research on how cooperation can be sustained by norms to punish non-cooperators, and punish those who don’t punish non-cooperators, etc.  For example, New Scientist:

The temptation to freeload – reap the rewards without contributing anything – often leads to rapidly disintegrating cooperation.  Previous research found that cooperation is promoted by allowing players to punish freeloaders: cooperative players would pay a small cost that enables them to inflict a loss on the offender.

The unstated moral behind most media stories on our biological instincts to cooperate seems to be that we would do better to empower and emphasize these instincts.  Such as, oh, taxing carbon, and shaming those who don’t tax carbon. Continue reading "The Dark Side of Cooperation" »

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What Do Nature Lovers Love?

Invasive.org explains who should care about invasive species.  Hikers, Campers:

Invasive plants, such as kudzu, English ivy and Japanese stilt grass can grow over trails and make them harder to follow and navigate through. Natural beauty is reduced by invasives. … Many invasive plants make hiking, camping, and other outdoor activities unpleasant. Exotic stinging needle … can take over camping sites, making it hard to find a good spot to camp.

Gardeners:

Landscape plants that seed freely, like privet … must be weeded out before they take over and displace plants that were painstakingly planted in your garden.

Consider also this review of Lyanda Huapt’s Crow Planet:

[Crows] may be the dark shape of our future. … She admits that she cannot quite love them. … Haupt also appreciates the birds’ intensely social biology. She tells stories of crow “funerals”, when the normally raucous birds gather silently around the body of a dead family member. She emphasises their startling intelligence. …

The crow’s ability to adapt to man-made environments – in contrast to the struggles of more fragile species – has made it one of the planet’s most successful bird species. But this achievement is the source of Haupt’s ambivalence: it’s everyone’s loss, she reminds us, if we create an environment that accommodates only tough survivor species like the crow.

While nature shows and nature lovers often give lip service to the wonders of natural selection, in fact they mainly love the particular species alive now.  When nature adapts to recent changes, nature lovers mostly disapprove.  Most folks react similarly when economic competition creates winners and losers; they say they approve of the competition that led to our current wealth, but they disapprove when new winners, e.g., Walmart or Borders, displace old losers, e.g., small stores.

In contrast, I’ve decided I mostly love the competitive process that produced these amazing things we see today.   So I expect to mostly approve of the future changes competition will bring.  Our descendants may not be beautiful to our eyes, but I expect them to be tough, smart, and scrappy, like the crow.

Added 2Oct: Mark Davis:

Only a few per cent of introduced species are harmful. Most are relatively benign; some, such as the honeybee, can even have beneficial effects. … With the exception of insular environments such as islands and lakes, there are very few examples of extinctions being caused by non-native species.

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