UC Berkeley
2015 Stories
What happens to plants that can’t spread their seeds?
Late fall and winter usually mean lots of squash soups and pumpkin pies. These hearty fruits (yes, they’re all fruits!) are easy to grow even in harsh conditions, and can be stored for a long time, making them cold-weather staples. But their ubiquity today belies a truth recently uncovered — these plants all nearly went extinct just a few thousand years ago. Why did they decline, and what brought them back? The answer to both questions, of course, is the same: evolution.
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What can we learn about our limbs from the limbless?
“The amniote phallus and limbs differ dramatically in their morphologies…” So begins a recent study published in the journal Developmental Cell. Though you can no-doubt easily distinguish a leg from a penis, it turns out that these functionally distinct appendages share similar genetic pathways. Scientists made this discovery in a surprising way — by examining the genomes of various snake species. Snakes do not have limbs, of course, so how could they have been the key to an insight about limb development?
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Is there anything truly surprising about Homo naledi?
On September 10, 2015, we humans added a new relative to our family tree when its discoverer, paleoanthropologist Lee Berger of the University of the Witwatersrand in South Africa, unveiled Homo naledi with great pomp and circumstance. The media was soon flooded with news about this “curious,” “weird,” “baffling,” and “bizarre” new species. But if you understand evolution, Homo naledi‘s mix of traits is not at all surprising. Furthermore, if you are well-versed in evolution, you would probably bristle at another adjective used again and again in the press to describe the species as “primitive.” Exaggerated and misleading word choices aside, there are remarkable aspects to this discovery. But the unknowns and not-yet-knowns — always a part of science — need to be understood before this new twig can be placed precisely on the tree of life.
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Mammals’ nocturnal past shapes sun sensitivity
As you soak up the last rays of the summer sun, here’s something to think about: if it weren’t for a quirk of our mammalian evolutionary past, your body could probably produce its own sunscreen. Back in May, researchers reported that they had discovered a mechanism by which zebrafish can generate a non-pigment-based sunscreen compound known as gadusol. They also found that the genes encoding the pathway for gadusol production are widespread; they are present in other fish species, as well as in amphibians, reptiles, and birds. This suggests that these genes arose early in vertebrate history and were passed down to many descendant lineages. This discovery is somewhat unsurprising, however, given the fact that all animal tissues are susceptible to damage from ultraviolet radiation. The protection these genes offer could represent a significant survival advantage. What is surprising about the new research is that the genes are completely absent in mammals. If our closest vertebrate relatives retained the genes for gadusol production, why didn’t mammals as well? The answer may lie in our deep evolutionary past, just as the mammalian lineage was arising…
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Avian flu adapts to human hosts
With multiple columns in the daily paper devoted to Ebola’s frightening rashes and bleeding, you’d be forgiven for forgetting that Ebola is far from the only emerging infectious disease that threatens human health today. Avian flu may be less dramatic and mainly infects birds, but it is no less deadly when it makes its way into a human host, with the worst strains killing 60% of people infected. We first wrote about the H5N1 avian flu back in 2005, but this is a bug that keeps coming back! Most recently, Egypt has experienced a surge of infections: 132 cases since January. All of them seem to have been passed to humans directly from infected birds. Now, new studies reveal that the Egyptian strain has evolved adaptations that allow it to more easily pass from bird to human, raising the possibility that the virus could soon evolve the ability to move from human to human — a development that would let this dangerous virus loose on humans all over the world, regardless of their proximity to infected poultry.
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Killer whales get a fitness boost after their offspring are grown
We all know that babies and youngsters need to be taken care of by a parent, but even adults can benefit from having a mom around — at least if your mom is a killer whale. New research announced last month describes how post-menopausal orcas help out their adult offspring by leading them to salmon foraging grounds. This help is especially important during years with fewer salmon. Through their many decades in the sea, older females seem to have learned where to find the fish when times are tough and pass this knowledge on to their adult offspring. This finding helps explain an evolutionary conundrum: if natural selection favors traits that allow an individual to pass its genes on to future generations, why would any organism stop reproducing?
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We are an island: the evolution of human parasite species
In recent years, the popular media has served up a message that might make your skin crawl: lice and bedbug infestations are on the rise and are getting harder to treat as these parasites evolve resistance to the pesticides we’ve used against them in the past. But did you ever stop to wonder how they’ve invaded our beds and bodies — not how a particular outbreak started, but how ultimately we wound up with these human bloodsuckers in the first place? Last month, new research highlighted the evolutionary beginnings — and future trajectory — of bedbugs. Taking a step back reveals that the origin of new parasites is just one example of well understood evolutionary processes.
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Want a new drug? Look to evolution
Last month, news outlets around the world heralded what could be a major medical breakthrough. In the midst of a public health battle against antibiotic resistant germs — which have been popping up with alarming frequency, not just in hospitals but in sick household pets and in meat from the supermarket — researchers announced the discovery of a powerful new antibiotic. Teixobactin easily cured mice of pneumonia and MRSA (an antibiotic resistant staph infection), and is likely to be effective against other deadly diseases such as anthrax. Yet this promising antibiotic has humble beginnings. It is produced by a soil bacterium discovered in a sample of dirt taken from a Maine field. Turning an evolutionary lens on this story reveals the explanation for teixobactin’s power and suggests that more new antibiotics might be literally in our own backyards.
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