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Wednesday, February 15, 2017

Book Review: Tears of the Cheetah - The Genetic Secrets of Our Animal Ancestors

"HIV, Ebola, and hepatitis.  Could other animals reveal natural genetic defenses to these same diseases?  Without such defenses, they will go extinct.  These species have no health insurance, no HMOs, no emergency rooms - only natural selection."

Today, genetics is such a constant topic in the news - in politics, science, and in culture - that it can be hard to remember just how new the field really is.  Although humans have been dabbling in genetics for millennia - ever since we began to domesticate our first plants and animals through artificial selection - our understanding of the science really dates back to the last few decades.  It's use in the study and conservation of animals is, in a sense, still brand new.

In the earliest days of conservation genetics, Dr. Stephen O'Brien was on that cutting edge.  Head of the Laboratory of Genomic Diversity at the National Institutes of Health (NIH), O'Brien and his colleagues were among the first to study the genetics of wild animals, including some of the most charismatic species on the planet, and unravel the hidden histories of their genome.  O'Brien shares many of these stories in Tears of the Cheetah: The Genetic Secrets of Our Animal Ancestors. 

What do cheetahs have to cry about, you may wonder?  If you follow the theory that Dr. O'Brien postulates, following his examination of their genetic codes, a lot (although the title is also a play reference to the black, tear-like stripes cheetahs have under their eyes).  According to the research that the NIH team conducted, wild cheetahs suffer from an astonishing lack of genetic diversity, the result of having their population wiped out until only a tiny handful of animals survived, from which the entire (relatively inbred) species we know today is descended from.  This brush with extinction was not human-caused, but rather a natural occurrence, which forced cheetahs through a genetic bottleneck - they survive, but in a somewhat compromised position due to their reduced diversity.

While what happened to cheetahs is a natural occurrence, a similar fate potentially awaits (or is befalling) other species as human activities - habitat loss, hunting, disease - destroy their populations and lower their diversity.  Dr. O'Brien takes his show on the road, so to speak, working with field biologists to study the genomes of humpback whales, lions, and orangutans.  With reduced gene diversity, the potential for species to adapt and evolve in the face of new environmental pressures is seriously threatened.  Taking a break from doom and gloom, he also sets off to answer what was one of the great taxonomic questions of the day - what is a giant panda - a bear... or a raccoon?

When not poking around in conservation genetics, Dr. O'Brien broadens his scope to look at the genetic pasts of humans, seeing what the genome can tell us about our own murky past as a species.  He also examines the history of our own diseases, from the bubonic plague of Medieval Europe to the HIV endemic which claimed the life of one of his family, all while explaining how the secrets of salvation may lie in our genomes (or in other genomes... he spends an instructive amount of time fiddling around with disease-ridden mice, searching for genetic anomalies which may represent cures for diseases).

And if none of that interests you, consider this - the author and his colleagues were the first scientists ever to use DNA evidence for an animal to help solve a murder case.  Ever NCIS or Bones episode you've ever watched that's used a strand of hair from the victim's cat to collar a killer?  They should be writing royalty checks to Stephen O'Brien.

Reading stories like that, it's hard not to be staggered by how far the science of genetics has come in the last few years.  When O'Brien testified that genetics proved that the hair found in a crime scene could only have come from one cat, the opposing attorneys loudly denounced it as "theoretical bullshit" and tried to convince the jury that it was pseudoscience.  Few laypersons understood such things back then, and few would be willing to accept them.  Genetic testing is now commonly carried out for medical, conservation, commercial, and legal purposes. 

The boundaries of our knowledge are continually being pushed.  And, as O'Brien and his colleagues came to realize as their scientific pursuits brought them in contact with some of the world's most imperiled species, the more we learn, the more responsibility we find ourselves with - both to ourselves, to our society, and to the natural world.

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