The fundamental structure of human populations has changed exactly twice in evolutionary history. The second time was in the past 150 years, when the average lifespan doubled in most parts of the world. The first time was in the Paleolithic, probably around 30,000 years ago. That’s when old people were basically invented.
Throughout hominid history, it was exceedingly rare for individuals to live more than 30 years. Paleoanthropologists can examine teeth to estimate how old a hominid was when it died, based on which teeth are erupted, how worn down they are, and the amount of a tissue called dentin. Anthropologist Rachel Caspari of Central Michigan University used teeth to identify the ratio of old to young people in Australopithecenes from 3 million to 1.5 million years ago, early Homo species from 2 million to 500,000 years ago, and Neanderthals from 130,000 years ago. Old people—old here means older than 30 (sorry)—were a vanishingly small part of the population. When she looked at modern humans from the Upper Paleolithic, about 30,000 years ago, though, she found the ratio reversed—there were twice as many adults who died after age 30 as those who died young.
Excerpt from an article written by Laura Helmuth at Slate. Continue THERE
In the past few decades, scientists studying the eating habits of Earth’s creatures have noticed something strange: the babies of several species, from tiger sand sharks to fruit flies, are eating each other.
Thing is, they aren’t freaks of nature. And in fact, the mechanisms behind animal cannibalism are helping scientists ask–and answer–some important evolutionary questions. These three recent studies provide a glimpse into this gruesome diet and what it means for evolution.
Why paternity might still matter after fertilization
Sand tiger sharks have been known to have cannibalistic embryos since the 1980s, when detailed autopsies revealed embryos in the stomachs of other shark embryos. But a new study published in Biological Letters could give some clues as to why.
Female sand tiger sharks aren’t the most faithful–they tend to mate with multiple male partners. And if you’re a male sand tiger shark trying to further your lineage, it’s not just about the speed and strength of sperm. The competition continues even after the eggs turn to embryos. After about five months of gestation, the embryo to first hatch from its egg in utero (the female sand tiger shark has two uteri) begins to feed on its smaller siblings–specifically those fathered by a different male. Some litters may start at 12 but this alpha embryo will eat all but one, leaving its brother or sister from the same mister alive. So despite the litters starting out with various fathers, the offspring that make it through the gestational massacre tend to be from the same father–and they’re large and strong enough to survive potential predators after birth. “It’s exactly the same sort of DNA testing that you might see on Maury Povich to figure out how many dads there are,” Stony Brook University marine biologist and study author Demian Chapman told LiveScience.
Text and Image via POPSci. Continue THERE
In the mid-2000s, David Markovitz, a scientist at the University of Michigan, and his colleagues took a look at the blood of people infected with HIV. Human immunodeficiency viruses kill their hosts by exhausting the immune system, allowing all sorts of pathogens to sweep into their host’s body. So it wasn’t a huge surprise for Markovitz and his colleagues to find other viruses in the blood of the HIV patients. What was surprising was where those other viruses had come from: from within the patients’ own DNA.
HIV belongs to a class of viruses called retroviruses. They all share three genes in common. One, called gag, gives rise to the inner shell where the virus’s genes are stored. Another, called env, makes knobs on the outer surface of the virus, that allow it to latch onto cells and invade them. And a third, called pol, makes an enzyme that inserts the virus’s genes into its host cell’s DNA.
It turns out that the human genome contains segments of DNA that match pol, env, and gag. Lots of them. Scientists have identified 100,000 pieces of retrovirus DNA in our genes, making up eight percent of the human genome. That’s a huge portion of our DNA when you consider that protein coding genes make up just over one percent of the genome.
Excerpt form an article written by Carl Zimmer. Continue HERE
32 year-old Dmitry Itskov believes technology will allow him to live forever in a hologram body. His ‘2045 initiative’ is described as the next step in evolution, and over 20,000 people have signed up on Facebook to follow its progress, with global conferences planned to explore the technology needed.
‘We are in the process of creating focus groups of experts,’ said Itskov. ‘Along with these teams, we will prepare goal statements and research programs schedules.’ The foundation has already planned out its timeline for getting to a fully holographic human, and claims it will be ready to upload a mind into a computer by 2015, a timeline even Itskov says is ‘optimistic’.
‘The four tracks and their suggested deadlines are optimistic but feasible,’ he said of the foundation’s site.
‘This is our program for the next 35 years, and we will do our best to complete it.’
The ultimate aim is for a hologram body.
‘The fourth development track seems the most futuristic one,’ said Itskov.
‘It’s intent is to create a holographic body. Indeed, its creation is going to be the most complicated task, but at the same time could be the most thrilling problem in the whole of human evolution.’
New York State first began issuing paper licenses to chauffeurs in 1910, and the shape, form and style have changed over the past century, adapting to new laws and technologies. The following is a sampling of how the license has evolved. See More HERE
To put a human face on our ancestors, scientists from the Senckenberg Research Institute used sophisticated methods to form 27 model heads based on tiny bone fragments, teeth and skulls collected from across the globe. The heads are on display for the first time together at the Senckenberg Natural History Museum in Frankfurt, Germany. Continue HERE
Text and Images via Discovery.