Extinction is a fact of modern life. Humanity's relentless encroachment on the wilderness has marred the diversity of life with conspicuous gaps where the Tasmanian tiger, the Passenger Pigeon, the Ivory-billed Woodpecker, and countless others used to be. As these extinctions accumulate, the Earth inches closer and closer to its sixth mass extinction. We are all too familiar with the concept of mass extinction - a disaster strikes and sets off a chain of events that result in a massive die-off. But you may not have considered what comes next: what happens to surviving species in the wake of a massive extinction event? Recent research suggests that mass extinctions shake up life on Earth in surprising ways.
In the next few months, college students across the country will be offered the chance to save a life by swabbing cells from the insides of their cheeks and registering as a potential marrow donor with Be The Match The Give A Spit About Cancer campaign, which launched in October, helps college students organize marrow donor registry drives. The cells collected in these drives are used to figure out who might be able to donate marrow or blood stem cells to a patient with a life-threatening disease like leukemia. While ethnicity is irrelevant to most medical procedures, marrow and blood stem cell transplants are an exception to this rule.
This month, the World Health Organization announced that tuberculosis cases are on the decline for the first time in at least 20 years. We seem finally to be winning what has been a very long battle. Tuberculosis bacteria have been attacking us since modern humans began to migrate out of Africa around 40,000 years ago. If you enjoy classic literature, you'll be familiar with the cough, fever, and weight loss of consumption (the old-fashioned term for tuberculosis), which used to be a near certain death sentence. That changed when the aminoglycoside antibiotic streptomycin was discovered in 1943.
Though we often think of evolution as occurring at a snail's pace, one fish species is highlighting just how quickly evolution occurs in the right circumstances. Between 1947 and 1976, General Electric released more than a million pounds of PCBs into the Hudson River. PCBs can kill fish and seabirds and have been linked to cancer and other serious health problems in humans. PCBs were banned in 1979, but the toxins have remained at high levels in the Hudson because they settle into the sediments on the bottom of the river and don't break down. Now, scientists have discovered that, over the past 60 years, one bottom-feeding fish species, the Atlantic tomcod, has evolved resistance to PCBs.