What’s the News: The human brains, capable as it is of amazing mental feats, comes with a downside: it shrinks as we get older, contributing to memory loss, reduced inhibitions, and the other cognitive dysfunctions of age. But even chimpanzees, our closest living relatives, don’t suffer this sort of brain loss, according to a study published online yesterday in Proceedings of the National Academy of Sciences. This unusual shrinkage of the human brain, the researchers say, may be a result of our long lifespan. (more…)
Posts Tagged ‘primates’
Human Brains Shrink As They Age, Perhaps From the Weight of Years
Orangutan Genome: The Orange Apes Evolved at Their Own Quirky Pace
Welcome to the family of critters with sequenced genomes, orangutans. In Nature this week, scientists unveil the draft DNA sequencing of our great ape cousins—the only great apes that live exclusively in Asia.
The researchers assembled the draft genome of the female Sumatran orangutan (Pongo abelii) using a whole-genome “shotgun” strategy, an old-fashioned approach that cost about $20 million. In addition, the researchers gathered sequence data from five wild Sumatran orangutans and five Bornean orangutans (Pongo pygmaeus) using a faster and thousandfold cheaper next-generation platform. [LiveScience]
What did scientists find in there? For one thing, orangutans share about 97 percent of the their genome with humans, compared to the 99 percent we famously share with chimpanzees. The two orangutan species—inhabiting the Indonesian islands of Borneo and Sumatra—diverged about 400,000 years ago, lead author Devin Locke says. That’s much more recently than scientists had thought.
They also discovered that over the last 15 million years, orangutan DNA changed at a different rate than either ours or chimps’. Orangutans have undergone fewer mutations of the DNA, have a lower gene turnover rate, and have fewer duplicated DNA segments.
Study: Young Female Chimps May Use Sticks as Dolls
From Ed YongIn Kibale National Park, Uganda, female chimps have taken to carrying sticks around with them. There’s nothing obviously unusual about that – chimps are clever tool-users, who use sticks as probes, projectiles and spears. But these chimps aren’t doing very much with their sticks – they simply hold and cradle them while they go about their usual business.
Sonya Kahlenberg and Richard Wrangham think they know why. They suggest that the stick-carrying chimps are playing at being mothers. Their sticks are the chimp equivalents of human dolls and the chimps treat them like pretend infants.
Kahlenberg and Wrangham present plenty of evidence to make this case, but their final suggestion—that this could be evidence of something that existed be humans split from chimps—is more of a leap. It is possible. But it’s also possible that even if the two scientists are right about what the behavior means, it could have evolved separately in chimps in the time since the split.
For more detail about all of this, check out the rest of Ed’s post at Not Exactly Rocket Science.
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Into Africa: Did the Earliest Primates Migrate From Asia?
You know the “out of Africa” story: how our ancestors left the savannas where humanity grew up and trekked outward to other continents. Today in Nature, however, a new study of 40 million-year-old fossils argues that an “into Africa” story predates the other narrative: that the animals that would eventually evolve into apes like us and monkeys came from Asia into Africa.
These fossil teeth found in Libya belong to early anthropoids, according to the scientists. The team found several different species in this location.
The new fossils are about 38 to 39 million years old, and none of the animals would have weighed more than 500 grams [just more than 1 pound], conclude a team led by Jean-Jacques Jaeger, a palaeontologist at the University of Poiters, France. Their diminutive size fits in with previous research suggesting that early anthropoids started small and eventually evolved ever bigger bodies. [Nature]
Mirror, Mirror: Study Says Monkeys May Recognize Their Own Images
Luis Populin never meant to study whether monkeys recognize themselves in the mirror. As DISCOVER blogger Carl Zimmer notes at the Loom, Populin’s team was working on a different project that required putting mirrors in monkey cages to stimulate their brains. Quite by accident, he noticed that monkeys with electrodes attached by the researchers spent an awful long time gawking at themselves in the mirrors.
The researchers published their findings this week in PLoS One, in which they write:
We hypothesize that the head implant, a most salient mark, prompted the monkeys to overcome gaze aversion inhibition or lack of interest in order to look and examine themselves in front of the mirror. The results of this study demonstrate that rhesus monkeys do recognize themselves in the mirror and, therefore, have some form of self-awareness.
For a video of a monkey checking itself out in the mirror, as well as much more detail about the study, its implications, and other primatologists’ doubts about it, check out Zimmer’s post.
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Image: Populin et. al.
After 9 Years Retirement, Lab Chimps May Return to Medical Testing
The governor of New Mexico wants a say in the future of 168 chimpanzees, and has pulled scientists, government officials, and even Jane Goodall into the debate.
The chimps in question are currently living (and have been for the last ten years) in a research reserve in the town of Alamogordo in New Mexico. They were all previously used as lab animals, where they are used to test and study HIV and Hepatitis C, life-threatening human diseases which don’t grow in any other animals.
The chimps were removed from laboratory testing after being taken from the Coulston Foundation, a research facility that was found to be abusing and neglecting its primate residents. The Alamogordo reserve was given the ten-year contract to house and care for the animals in 2001.
Harold Watson, who heads the chimpanzee research program for the National Center for Research Resources, said that with the end of the contract, it only makes sense to use the chimps for their original purpose. [The New York Times]
Malaria Came From Gorillas to Humans, and From Humans to Bonobos
Several million years ago, Plasmodium falciparum – the parasite that causes most cases of human malaria – jumped into humans from other apes. We’ve known as much for decades but for all this time, we’ve pinned the blame on the wrong species. A new study reveals that malaria is not, as previously thought, a disease that came from chimpanzees; instead it’s an unwanted gift from gorillas.
Until now, the idea of chimps as the source of human malaria seemed like a done deal.
Check out the rest of this post at DISCOVER blog Not Exactly Rocket Science.
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Image: Wikimedia Commons
HIV’s Primate Precursor Is Very Old. Why Did It Jump To Humans So Recently?
HIV became an epidemic in the human population just in the 20th century. Its precursor found in primates, called simian immunodeficiency virus or SIV, could be not just hundreds of years old, but tens of thousands of years old, according to a study out in Science.
Preston Marx and colleagues studied the monkeys of Bioko, an island off West Africa that has been cut off from the mainland for 10,000 years. By studying the way SIV evolved in that isolated population, the team calculated that the virus is at least 32,000 years old, and possibly much, much older. Says Marx:
“The biology and geography of SIV is such that it goes from the Atlantic Ocean to the Indian Ocean all the way to the tip of Africa. … It would take many, many thousands of years to spread that far and couldn’t have happened in a couple of hundred years.” [AFP]
Bonobo Mothers Help Their Sons Get More Sex
From Ed YongMost human men would be appalled at the idea of their mothers helping them to get laid. But then again, we’re hardly as sexually carefree as bonobos. While these apes live in female-led societies, the males also have a strict pecking order. For those at the bottom, mum’s assistance may be the only thing that allows them to father the next generation.
Martin Surbeck from the Max Planck Institute for Evolutionary Anthropology found that bonobo mothers will help to usher their sons into the best spots for meeting females, and they’ll sometimes help their sons in conflicts with other males. Thanks to their help, their sons get more shots at sex than they would otherwise.
Read the rest of this post at Not Exactly Rocket Science.
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Image: iStockphoto
Renowned Harvard Primatologist Found Guilty of Scientific Misconduct
An investigation of Marc Hauser, a Harvard University psychology professor who studies primate behavior and animal cognition, came to a head on Friday with a letter from Harvard’s dean confirming eight instances of scientific misconduct.
The exact offenses are still unclear, but three papers have received or are receiving modifications. The papers include a 2002 Cognition article (retracted), a 2007 article in Proceedings of the Royal Society B (received an addendum), and a 2007 article in Science.
From Harvard Dean Michael Smith’s letter:
[T]he investigating committee found problems with respect to the three publications mentioned previously, and five other studies that either did not result in publications or where the problems were corrected prior to publication. While different issues were detected for the studies reviewed, overall, the experiments reported were designed and conducted, but there were problems involving data acquisition, data analysis, data retention, and the reporting of research methodologies and results. [Chronicle of Higher Education]
While Harvard has not been forthcoming with the details, one former research assistant provided the Chronicle of Higher Education with email exchanges between research assistants and Hauser, related to particular problems interpreting results from primate study.
A Weapon Against Ebola: Army Docs’ Treatment Helps Monkeys Survive
In this week’s Nature Medicine, a study brings a ray of success in researchers’ quest to fight the deadly viruses Ebola and Marburg. Testing a new approach on monkeys, scientists at the U.S. Army Medical Research Institute of Infectious Diseases saw most of the monkeys survive a normally fatal Ebola infection—and all of them who had Marburg lived.
Within an hour of infecting the primates, researchers gave them antisense phosphorodiamidate morpholino oligomers, or PMOs.
The morpholino oligomers are a new class of drugs in a family of what is known as antisense nucleotides. Antisense nucleotides are designed to bind tightly to specific areas of viral messenger RNA, blocking replication. Such compounds already are being used to treat certain types of cancer and cytomegalovirus infections, and they are being tested against HIV [Los Angeles Times].
Crazy-Looking Redbearded Monkey Turned Up in Colombia
The good news: After decades of wondering whether this immaculately bearded monkey really existed, but not being able to confirm it because of never-ending violence in Colombia, scientists say they’ve finally found evidence of the Caqueta titi monkey. The bad news: Because of habitat destruction, the cat-sized redbeard primate is critically endangered.
The new species joins about 20 other titi monkeys known in the Amazon basin. They appear to be monogamous to a level that puts humans to shame, says expedition leader Thomas Defler, whose study (pdf) appears in Primate Conservation. The Caqueta monkey couples have about one child per year that they raise together, and that isn’t the end of their absurd adorableness. (more…)
4 Messages a Pantomiming Orangutan Might Be Trying to Convey
Stop patting yourself on the back. You’re not so special. Orangutans, a new study suggests, also use complex gestures or pantomimes to communicate.
Looking through twenty years worth of orangutan observations, researchers believe they have found 18 examples of pantomimes. The study, which appeared today in Biology Letters, supports the claim that we’re not unique when it comes to abstract communication and lends credence to other observations of great ape gesturing, according to lead researcher Anne Russon.
[Orangutans and chimpanzees were already known] to throw an object when angry, for example. But that is a far cry from displaying actions that are intentionally symbolic and referential–the behaviour known as pantomiming. “Pantomime is considered uniquely human,” says Anne Russon from York University in Toronto, Canada. “It is based on imitation, recreating behaviours you have seen somewhere else, which can be considered complex and beyond the grasp of most non-human species.” [New Scientist]
Of the eighteen observed orangutan pantomimes, four took place between orangutans and 14 between a human and an orangutan. If you ever find yourself in the Indonesian jungles, here are some examples of messages that you might expect:
An Active Orangutan Burns Fewer Calories Than a Lazy Human
When an orangutan swings through the trees like an acrobat in its rainforest habitat, it’s burning fewer calories than a human couch potato.
A new study by biological anthropologist Herman Pontzer has found that oragutans use less energy, pound-for-pound, than any other mammal–except for that all-time champion of metabolic lethargy, the tree sloth.
“You and I sitting in front of our computers use more energy each day than these orangutans that are walking around, and climbing around and socializing around their big enclosures,” Pontzer says. [NPR]
Fossil May Reveal When Humanity’s Ape Ancestors Split from Monkeys
Perhaps you’re one of those people who get their dander up when you hear creationists saying “I’m not descended from some monkey” not only for the obvious reason, but also because you can’t help but blurt out, “No, you mean ‘ape!’ We’re apes, not monkeys.”
Indeed, our superfamily, Hominoidea, split from the group labeled “old world monkeys” millions of years ago—but perhaps not as many million as we thought. In Nature this week, a team of scientists report on a 28-29 million year old fossil that appears to predate the split, meaning the separation would have happened more recently than other studies suggested.
The partial skull of this new creature, which the team dubbed Saadanius hijazensis, turned up in Saudi Arabia in February 2009.
