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SCIENCE IN MIND

Tree-climbing tribe provides new ideas about human evolution

The Twa of Uganda are able to bend their ankles to an extreme degree that lets them more easily climb to the highest treetops.

George H. Perry

The Twa of Uganda are able to bend their ankles to an extreme degree that lets them more easily climb to the highest treetops.

Several million years ago, human ancestors began striding around on two legs, in what was a key moment in the evolution of modern humans. But the question of whether each species of prehuman left treetops behind and made their home in grasslands has not always been easy to discern from fossils, which can provide conflicting evidence.

Now, a team of scientists from Dartmouth College that has been studying a former hunter-gatherer population in Uganda has found clues among living humans that further muddies the picture, making it clear that even a modern human foot can be useful in impressive feats of climbing.

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The group of people the researchers focused on, the Twa of Uganda, are former hunter-gatherers who in the last 15 years have had to leave the forest. The Twa are remarkable climbers, able without ropes and harnesses to clamber high into treetops to harvest honey.

The researchers took videos of the men to see whether they could understand the biomechanics of their climbing abilities and found that the Twa were able to bend their ankles to an extreme degree, bringing their shins close to the tree. In normal people, such flexing in the ankle would cause injury or broken bones.

“It is similar to what you see in chimpanzees, the angle we measured,” said Vivek Venkataraman, a graduate student at Dartmouth who led the research.

The study, published in the Proceedings of the National Academy of Sciences, does not prove that Lucy or any other prehuman species with a humanlike foot was spending a lot of time in the trees or was primarily a climber. But the study suggests that the urge to neatly divide prehuman species into categories — some that dwelled in the grasslands and others that lived in the trees like apes — may be too simplistic a way of thinking about the way those species lived.

Ignorance isn’t just bliss; it might be a scientific necessity

I’m always struck when I hear a scientist talk about the virtues of not knowing things. This does not mean being stupid, dumb, or uneducated. Instead, scientists say again and again that the state of mind where you really don’t know the answer — and you know you don’t — can be the most productive way to attack a problem.

The great physicist Richard Feynman said it best, probably: “Science is the belief in the ignorance of experts.” But it bears repeating and it’s one of those ideas that resonates outside of the lab, too.

In a Q&A that appeared in the journal Nature last year, the physicist William Phillips, a Nobel laureate who works at the National Institute of Standards and Technology in Gaithersburg, Md., said that scientists are fortunate to live in ignorant times.

“We live in an incredibly exciting time for physics. We don’t know what 96 percent of the universe is made of. . . . When I was a graduate student we didn’t know what we didn’t know about the universe. Now we know what we don’t know — and that is really a good place to be,” Phillips told Nature.

In a paper published in Behavioural Processes a few years ago, Nate Kornell, a psychology professor at Williams College, studied the virtues of ignorance, finding that too much information can hold a person back from learning.

Kornell and his coauthor, Lisa K. Son, recounted one informal test of the pitfalls of being too knowledgeable, in which mathematicians and historians were quizzed on a list of categories and names. They were asked to say whether 90 names were properly matched in one of three categories: math, history, or sports. Experts in each field were more reluctant to respond “don’t know” when facing questions about the turf that they had spent their lives studying, versus domains outside their area of expertise. They also more often said that made-up names belonged in a category when it was their specialty.

Erin K. O’Shea, a Harvard University professor and the new chief scientific officer of the Howard Hughes Medical Institute, said in an interview earlier this year that one of the problems with how science is funded is that in the race to get funding, people often propose experiments for which they already know the outcome.

“They are judged in a way such that it needs to be clear you can do the work and it’s not too risky and no matter what happens we’re going to learn something,” O’Shea said. “And that leads to incremental work, the next obvious step.”

So, in 2013, let go of some of those preconceptions and blunder around a little. Who knows what you’ll find?

BU researchers give antibiotics a ‘helper’ to fight infections

Researchers from Boston University have developed a new approach to attack bacterial infections by making them more susceptible to traditional antibiotics. The novel technique could allow scientists to identify sidekick drugs that spur bacteria to increase their production of compounds that damage their own DNA, and make it easier for conventional therapies to deal a fatal blow.

The strategy, described Sunday in the journal Nature Biotechnology, could offer a powerful approach to fighting an increasing number of resistant infections, which has become a national priority.

Instead of focusing on new classes of antibiotics, the Boston University team looked at ways to enhance existing drugs.

“It’s in the spirit of, ‘Look, we’ve got pretty good antibiotics — can we find ways to extend their shelf lives and make them better?’ ” said James J. Collins, a BU biomedical engineer who led the work.

In the new study, researchers examined a vast flow chart of the metabolism of E. coli to understand how the bacteria naturally create compounds, called reactive oxygen species, that damage the fundamental building blocks of a cell, such as DNA and proteins. They looked for and found genes that reduce production of the harmful compounds. Blocking those genes could have the opposite effect and increase the amount of reactive oxygen species. When they deleted those genes and treated the bacteria with traditional antibiotics, the combination approach made the antibiotics markedly more effective at killing bacteria.

Carolyn Y. Johnson can be reached at cjohnson@globe.com. Follow her on Twitter @carolynyjohnson.
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