kottke.org posts about humans
Old people, like those who live to be older than 30, didn't exist in great numbers until about 30,000 years ago. Why is that? Anthropologist Rachel Caspari speculates that around that time, enough people were living long enough to function as a shared cultural hard drive for humans, a living memory bank for skills, histories, family trees, etc. that helped human groups survive longer.
Caspari says it wasn't a biological change that allowed people to start living reliably to their 30s and beyond. (When she looked at other populations of Neanderthals and Homo sapiens that lived in the same place and time, the two different species had similar proportions of old people, suggesting the change was not genetic.) Instead, it was culture. Something about how people were living made it possible to survive into old age, maybe the way they found or stored food or built shelters, who knows. That's all lost-pretty much all we have of them is teeth-but once humans found a way to keep old people around, everything changed.
Old people are repositories of information, Caspari says. They know about the natural world, how to handle rare disasters, how to perform complicated skills, who is related to whom, where the food and caves and enemies are. They maintain and build intricate social networks. A lot of skills that allowed humans to take over the world take a lot of time and training to master, and they wouldn't have been perfected or passed along without old people. "They can be great teachers," Caspari says, "and they allow for more complex societies." Old people made humans human.
What's so special about age 30? That's when you're old enough to be a grandparent. Studies of modern hunter-gatherers and historical records suggest that when older people help take care of their grandchildren, the grandchildren are more likely to survive. The evolutionary advantages of living long enough to help raise our children's children may be what made it biologically plausible for us to live to once unthinkably old ages today.
Did you know that there are new human beings? Like, not just new human babies but new species of humans? And not just new species of humans, but new species of humans who lived at the same time as, and even possibly bred with, modern humans, aka us? (Helloooooo, mesofacts.)
If you've read kottke.org over the years, you've likely heard of Homo floresiensis (aka Flores man, aka Hobbits), a species whose remains were discovered in present-day Indonesia in 2003. Homo floresiensis lived 95,000 to 13,000 years ago and stood about three feet high.
In this month's National Geographic, Jamie Shreeve tells the story of the 2010 discovery of the Denisovans, hominids who lived in modern-day Russia as late as 40,000 years ago. Only a handful of bone fragments and teeth have been recovered, but DNA and other evidence suggests that Denisovans, Neanderthals, and modern humans lived together in the same place and interbred.
By the time of the Denisova symposium, Pääbo and his colleagues had published first drafts of the entire Neanderthal and Denisovan genomes. Reading so many more pages allowed Pääbo and his colleagues, including David Reich at Harvard University and Montgomery Slatkin at the University of California, Berkeley, to discover that human genomes today actually contain a small but significant amount of Neanderthal code -- on average about 2.5 percent. The Neanderthals still may have been swept into extinction by the strange, high-browed new people who followed them out of Africa, but not before some commingling that left a little Neanderthal in most of us, 50,000 years later. Only one group of modern humans escaped that influence: Africans, because the commingling happened outside that continent.
Although the Denisovans' genome showed that they were more closely related to the Neanderthals, they too had left their mark on us. But the geographic pattern of that legacy was odd. When the researchers compared the Denisovan genome with those of various modern human populations, they found no trace of it in Russia or nearby China, or anywhere else, for that matter -- except in the genomes of New Guineans, other people from islands in Melanesia, and Australian Aborigines. On average their genomes are about 5 percent Denisovan. Negritos in the Philippines have as much as 2.5 percent.
In 2012, evidence emerged of a possible new human species, the Red Deer Cave people, who lived in what is now southern China.
The Red Deer Cave dwellers' unusual features included a flat face, a broad nose, a jutting jaw that lacked a chin, large molar teeth, a rounded braincase with prominent brow ridges, and thick skull bones, the researchers say.
Their brains were "moderate in size," Curnoe added.
Despite this seemingly primitive human design, radiocarbon dating of charcoal from the fossil deposits suggests the Red Deer Cave people lived just 14,500 to 11,500 years ago, the team says-a time by which all other human species, such as Neanderthals, are thought to have died out.
As with the other potential new human species, and as is proper in science, there is some skepticism about the Red Deer Cave people.
The team's suggestion that the Red Deer Cave people are somehow evolutionarily unique is receiving a skeptical reception from other scientists.
Physical anthropologist Erik Trinkaus described the findings as "an unfortunate overinterpretation and misinterpretation of robust early modern humans, probably with affinities to modern Melanesians"-indigenous peoples of Pacific islands stretching from New Guinea to Fiji (map).
"There is nothing extraordinary" about the newly announced fossil human, added Trinkaus, of Washington University in St. Louis, via email.
Philipp Gunz, of Max Planck Institute for Evolutionary Anthropology in Germany, isn't convinced by the study team's interpretation either.
"I would be surprised if it really was a new human group that was previously undiscovered," said, Gunz, also a physical anthropologist.
In the last few years, scientists have discovered that before Neanderthals went extinct around 30,000 years ago, they interbred with modern humans. As a result, many humans alive today contain Neanderthal DNA in their genomes, typically between 1-4%.
Yesterday, a few of the editors at The Atlantic had their genes analyzed for Neanderthal DNA: Alexis Madrigal had 3.6%, Steve Clemons had 4.3%, and James Fallows had 5%. Personal genetic information company 23andMe added the ability to determine your Neanderthal DNA percentage a few months ago and it turns out 2.7% of my DNA is from Neanderthals, compared to 2.5% for the average 23andMe user.
If you have a 23andMe acct, you can check your percentage by logging in and going to "Ancestry Labs" in the sidebar.
Elephants were the "perfect food package" for pre-human hominids (they were slow with a good fat-to-protein ratio) and their extinction in the Middle East (and Africa) caused those hominids to evolve to be more like modern humans.
When elephants began to die out, Homo erectus "needed to hunt many smaller, more evasive animals. Energy requirements increased, but with plant and protein intake limited, the source had to come from fat. He had to become calculated about hunting," Ben-Dor says, noting that this change is evident in the physical appearance of modern humans, lighter than Homo erectus and with larger brains.
Whoa, watch the video at the top of this article to see how the human face develops in the womb from an age of one-month to ten weeks. It all just comes together right at the end!
If you watch it closely, you will see that the human face is actually formed of three main sections which rotate and come together in an unborn foetus.
The way this happens only really makes sense when you realise that, strange though it may sound, we are actually descended from fish.
The early human embryo looks very similar to the embryo of any other mammal, bird or amphibian -- all of which have evolved from fish.
Your eyes start out on the sides of your head, but then move to the middle.
The top lip along with the jaw and palate started life as gill-like structures on your neck. Your nostrils and the middle part of your lip come down from the top of your head.
There is no trace of a scar; the plates of tissue and muscle fuse seamlessly. But there is, however, a little remnant of all this activity in the middle of your top lip -- your philtrum.
The discovery of stone tools that are possibly 130,000 years old on the island of Crete may indicate that humans were seafaring far earlier than is commonly believed.
Archaeologists and experts on early nautical history said the discovery appeared to show that these surprisingly ancient mariners had craft sturdier and more reliable than rafts. They also must have had the cognitive ability to conceive and carry out repeated water crossing over great distances in order to establish sustainable populations producing an abundance of stone artifacts.
Internet, meet Ardi, the newest member of the human branch of the primate family tree.
Or rather, the oldest. Discovered in Ethiopia in 1994, Ardi is a 4.4 million-year-old partial skeleton of a female Ardipithecus ramidus.
The fossil puts to rest the notion, popular since Darwin's time, that a chimpanzee-like missing link -- resembling something between humans and today's apes -- would eventually be found at the root of the human family tree. Indeed, the new evidence suggests that the study of chimpanzee anatomy and behavior -- long used to infer the nature of the earliest human ancestors -- is largely irrelevant to understanding our beginnings.
Ardi instead shows an unexpected mix of advanced characteristics and of primitive traits seen in much older apes that were unlike chimps or gorillas. As such, the skeleton offers a window on what the last common ancestor of humans and living apes might have been like.
This is a major discovery; Science is devoting a special issue to the find with 11 detailed peer-review papers and general summaries. I expect we'll be hearing more about this in the coming weeks as all that science filters through the lay media. (thx, jeff)
Some poop in a cave in Oregon has been dated to more than 14,000 years ago and identified as human, adding to other evidence that humans inhabited the Americas before the well-known Clovis people.
Other archaeologists agreed that the findings established more firmly than before the presence of people on the continent at least 1,000 years before the well-known Clovis people, previously thought to be the first Americans. Recent research at sites in Florida and Wisconsin also appears to support the earlier arrivals, and a campsite in Chile indicates migration deep into South America by 14,600 years ago.
Speaking of memes, Susan Blackmore theorizes that humans are just machines for propagating them.
Memes are using human brains as their copying machinery. So we need to understand the way human beings work.
Up until very recently in the world of memes, humans did all the varying and selecting. We had machines that copied -- photocopiers, printing presses -- but only very recently do we have artificial machines that also produce the variations, for example (software that) mixes up ideas and produces an essay or neural networks that produce new music and do the selecting. There are machines that will choose which music you listen to. It's all shifting that way because evolution by natural selection is inevitable. There's a shift to the machines doing all of that.
When asked what the future will look like, she says, "it will look like humans are just a minor thing on this planet with masses (of) silicon-based machinery using us to drag stuff out of the ground to build more machines."
The pace of human evolution has accelerated greatly over the last 40,000 years, partially due to our population growth.
The brisk rate of human selection occurred for two reasons, Dr. Moyzis' team says. One was that the population started to grow, first in Africa and then in the rest of the world after the first modern humans left Africa. The larger size of the population meant that there were more mutations for natural selection to work on. The second reason for the accelerated evolution was that the expanding human populations in Africa and Eurasia were encountering climates and diseases to which they had to adapt genetically. The extra mutations in their growing populations allowed them to do so.
Dr. Moyzis said it was widely assumed that once people developed culture, they protected themselves from the environment and from the forces of natural selection. But people also had to adapt to the environments that their culture created, and the new analysis shows that evolution continued even faster than before.
Looks like this study answers the "Is Evolution Over?" question.
A timeline of human history (mostly sex and violence) by Milo Manara. NSFW.
Some recent research on the wrist bones of the so-called hobbit skeleton suggests that Flores man is an ancestor of modern humans and not just diseased homo sapiens. The debate continues. (via npr)
Humans are the animal world's best distance runners...we can run long distances relatively fast without overheating. "Once humans start running, it only takes a bit more energy for us to run faster, Lieberman said. Other animals, on the other hand, expend a lot more energy as they speed up, particularly when they switch from a trot to a gallop, which most animals cannot maintain over long distances." (via beebo)
I thought that said "Netherlanders"...I was ready to put that in the "odd things I didn't know about the Dutch" column.
An evolutionary theorist has predicted that humans may split into two sub-species: "the genetic upper class would be tall, slim, healthy, attractive, intelligent, and creative and a far cry from the 'underclass' humans who would have evolved into dim-witted, ugly, squat goblin-like creatures."
Watched America's Stone Age Explorers on PBS this evening, a summary of recent findings about who the first Americans were, where they came from, and when they arrived. Recent genetic and archeological evidence suggests they arrived earlier than generally accepted and may have originated from Europe rather than Asia.
Recently discovered human remains suggest that metrosexuals lived in Iron Age Ireland. One man's fingernails were manicured and his hands indicated he'd never done manual labor while the other wore hair gel imported from France and Spain. No word on if they wore their shirts tucked or untucked.
Further discovery of Homo floresiensis bones have strengthened researchers' argument that the so-called Hobbit is a new and distinct human species. More on Flores man at Nature, which is doing a weekly podcast now.
A US antropologist says that weaker toes found in human skeletons from 26,000-40,000 years ago indicates when humans started wearing sturdy shoes.
Robotics research suggests that Lucy walked upright like humans. Lucy, discovered in 1974 in Ethiopia, is a 3.2 million year old Australopithecus afarensis skeleton.
40,000 year-old human footprints found in Mexico. Humans are thought to have come to the Americas only 11,000 years ago.