UC Berkeley
2007 Stories
Evolution from a virus’s view
The new disease making the rounds this winter sounds like a Steven Spielberg movie in the making: a common cold virus, which spreads via casual contact, mutates into a virulent form that hospitalizes and sometimes kills its victims. Touted last month as the “killer cold,” Adenovirus-14 is far from fantasy, but neither is it scary enough to make a blockbuster. In the past 18 months, the virus has caused just 10 deaths — a minor toll when compared to the 36,000 caused by the flu in an average year. Why hasn’t Adenovirus-14 lived up to the threat advertised in headlines? Evolution helps explain why some bugs are killers, why others are not, and what chance a mutant cold virus has of reaching epidemic proportions.
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Genealogy enthusiasts mine DNA for clues to evolutionary history
If you’ve ever sat down with a great aunt to reconstruct your family history, wondered if you might be related to Genghis Khan, or tried to calculate what portion of your genes come from that rowdy great-grandparent that your dad never wants to talk about, you might be tempted to try out the latest in genealogy research: DNA. Last month saw the launch of GeneTree.com, a business combining social networking with genetic testing. For a fee, GeneTree will use the DNA in a sample of your cheek cells (collected with a special mouthwash) to “discover your deepest ancestral roots.” With advances in DNA technology, some genetic tests are relatively easy to perform, and GeneTree joins more than 20 other companies aiming to unravel ancestry via DNA tests. But what are the limits of these tests? An evolutionary perspective helps reveal whether these companies can deliver on their promises.
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Another perspective on cancer: Evolution within
This month, pink products — from sneakers to vacuum cleaners — will pop up on store shelves. Even Campbell’s Soup will shed its tomato red label in favor of pearly pink. Whatever your opinion on the pink campaign to raise awareness of and research dollars for breast cancer, the cause is unlikely to escape your notice during October, National Breast Cancer Awareness Month. Since nearly 200,000 women in the United States will be diagnosed with breast cancer this year alone, funding for research has the potential to improve the quality of life and survival odds for many millions of people. But despite increased attention and funding, the cure for this and other cancers has remained notoriously elusive. Viewing cancer through the lens of evolution helps explain why a cure seems to remain just out of reach and points the way toward new treatments.
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When it comes to evolution, headlines often get it wrong
“Fossils challenge old evolution theory,” proclaimed Fox News, while the Salt Lake Tribune, bragged that “University scientists defy evolution view!” From the headlines trumpeted in some media outlets, one might imagine evolution as a theory in crisis — publishers struggling to rewrite textbook chapters before print deadlines, biologists running from their labs, tearing their hair. In fact, nothing could be further from the truth. Last month, when scientists published a description of newly discovered hominid fossils and suggested that they might prompt a minor revision of the human family tree, biologists and paleoanthropologists considered the additional evidence with interest and the authors’ interpretation with a healthy skepticism typical of science. Since events that occurred more than a million years ago are difficult to reconstruct, paleontologists welcome additional lines of evidence relevant to those details and expect our understandings of them to be refined as evidence accumulates. The fossils suggested reexamining a few hypotheses about hominid evolutionary history, but nothing about them called evolutionary theory into question. In fact, the new evidence fit well with everything we know about how evolution works. Unfortunately, some influential media outlets’ quick gloss on this discovery exaggerated its implications and distorted the true nature of science…
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Cheating cheetahs prosper
Philandering males, sneaking around behind their partners’ backs or openly canoodling, are a stock character on Animal Planet. Male lions, male chimps, and male elephant seals (along with many others) play the Casanovas, pairing up with multiple females. But now researchers have revealed that cheetahs buck this sexual stereotype. According to the May 2007 study, female cheetahs seem to be at least as promiscuous as their male counterparts. Females frequently mate with several different males while they are fertile and are then likely to bear a single litter of cubs fathered by multiple males — making many of the cubs within a single litter only half-siblings. This discovery has important implications for the conservation of these endangered animals. Though it conflicts with the idea that cheaters never prosper, evolutionary theory suggests that, in this case, cheating may be exactly what the doctor ordered…
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Evolving conservation strategies
Wolves, grizzlies, and other endangered species dodged a bullet last month when the Department of the Interior briefly considered a new interpretation of the Endangered Species Act. The Act protects species that are at risk of going extinct throughout a significant portion of their range. This range has always included areas where the species historically lived (even if they’ve since been driven out). However, the interpretation proposed last month would have changed that, protecting a species only over the range in which it currently lives — a decision that could have made it more difficult for a dwindling species to make the list. Scientists responded by signing on to a letter protesting the decision and, in so doing, seem to have caught someone’s ear. On May 25, the Department announced that it would ditch the initiative. The Endangered Species Act exemplifies traditional conservation efforts to preserve historical diversity — but today, evolutionary theory is taking conservation in a whole new direction…
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Seeing the tree for the twigs
When humans consider evolutionary history, we usually view the tree of life from the vantage point of our own tiny twig. We trace the hominid branch seven million years back in time — passing long-lost relatives along the way (our Neanderthal cousins, Great Aunt Lucy…) — until we reach the ancestor linking us with other primates and marvel, “Look how far we’ve come!” But just how impressive is our own evolution into a bipedal, big-brained, blabbering hominid? Now new research reveals that our own evolution may be more of a small hop in comparison to the leap taken by our closest living relative, the chimpanzee, and encourages us to take a broader view of the tree of life.
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Got lactase?
In the US and many other countries, we’ve certainly “got milk,” but not everyone can enjoy it. For around 10% of Americans, 10% of Africa’s Tutsi tribe, 50% of Spanish and French people, and 99% of Chinese, a tall cold glass of milk means an upset stomach and other unpleasant digestive side effects. In fact, most adults in the world are lactose intolerant and cannot digest lactose, the primary sugar in milk. And yet, regardless of our ancestry, most of us began our lives happily drinking milk from a bottle or breast — so what happened in the intervening time? Why do so many babies enjoy lactose and so many adults avoid it? Lactose is broken down by a protein called lactase, which acts as a pair of molecular scissors, snipping the lactose molecule in two. Anyone who drank milk as a baby carries a working version of the gene that codes for lactase. In lactose tolerant individuals, that gene keeps working into adulthood, producing the protein that digests lactose and makes eating ice cream a pleasant experience. But in people who are lactose intolerant, that lactase gene is switched off after weaning. Now, new research reveals that the Stone Age ancestors of European dairy-lovers probably couldn’t digest milk either. So how did they get from bellyaches to milk mustaches? The answer is an evolutionary story that takes us from the milkmaids of the Alps to the Maasai herdsmen of Africa.
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A chink in HIV’s evolutionary armor
Since it made the evolutionary leap to humans from chimpanzees, HIV/AIDS has infected around 1% of the global population and in 2005 alone, killed almost three million people. Much of HIV’s continued spread can be traced to its evasion of both the human immune system and our vaccines. Now that could be changing. Last month, a team of researchers led by Peter Kwong of the National Institutes of Health revealed the details of a molecular dance between the virus and its human host cells that could pave the way for a long-awaited vaccine. The secret is in this picture. Here, an antibody (shown in green) latches onto a HIV molecule (shown in red) at its site of vulnerability (shown in yellow), thus interfering with the virus’s ability to infect new cells. What makes this yellow site HIV’s weak point? The answer is an evolutionary one…
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The other green (r)evolution
These days, corn seems to be going high tech, as the U.S. and other countries shift their attention to corn-based ethanol fuels in response to dwindling oil supplies. And the corn market is feeling this demand for the “fuel of the future”: in recent months, corn prices have skyrocketed, in Mexico the cost of tortillas has soared, and many U.S. farmers have planned to invest more of their fields in corn, passing up soybeans, wheat, and cotton. So is corn the next new “green” technology? Well, maybe — but in fact, corn as we know it has always been high-tech. That plump ear of corn in the farmer’s market is just as much a product of human engineering as an iPod. Ten thousand years ago, there was no corn — there was just the weedy grass teosinte. Since then, humans have used evolution’s tool-kit to shape teosinte into the tall stalks of modern corn, joining in the other green revolution — the 6000 years of human history during which we transformed our lifestyles and environments by evolving all the major crops that we depend upon today: corn, rice, wheat, squash, millet, barley, banana, taro, tomato, potato, beans, and cotton. Now, scientists are learning more about exactly how we accomplished that feat.
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Evolutionary evidence takes the stand
Despite overwhelming evidence attesting to their innocence, last month six medical workers were sentenced to death in a Libyan trial. The crime with which the five Bulgarian nurses and one Palestinian doctor are charged is indeed horrifying. After an outbreak of HIV at the Al-Fateh hospital, the Libyan government accused the defendants of committing an act of bioterrorism by deliberately injecting 426 hospitalized children with HIV-tainted blood. The HIV strain is particularly virulent and has already contributed to the deaths of more than 50 of the infected children. The families of both the victims and the accused are enraged, and the controversy is escalating: the case has already seen one retrial and further appeals are likely. But what about science? What does the scientific evidence have to say?
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