Female brown recluse spider. Credit Matt Bertone, North Carolina State University.
This Halloween, you’re not likely to see many trick-or-treaters dressed as spiders. Google Trends pegs “Spider” as the 87th most searched-for Halloween costume, right between “Hippie” and “The Renaissance.” But don’t let your guard down. Spiders are everywhere.
“I grew up on a farm in Indiana and had the luxury of exploring and turning over rocks and being curious. Any feelings of being grossed out by spiders were rapidly replaced by my feelings of awe for how amazing and diverse these creatures are.”– Greta Binford”
More than 46,000 species of spiders creepy crawl across the globe, on every continent except Antarctica. Each species produces a venom composed of an average of 500 distinct toxins, putting the conservative estimate of unique venom compounds at more than 22 million. This staggering diversity of venoms, collectively referred to as the venome, has only begun to be explored. Continue reading “Exploring the Evolution of Spider Venom to Improve Human Health”
After mating about 55,000 pairs of fruit flies and sifting through 333,000 daughter flies, a research team found six sons that each had mutations in the same gene that helped make two fruit fly species unique from each other. Credit: Jim Woolace, Fred Hutch News Service.
Nitin Phadnis and Harmit Malik set out to conduct an experiment that could solve a century-old evolutionary puzzle: How did two related fruit fly species arise from one? Years after they began their quest, they finally have an answer.
The existence of a gene that helps make each of these fruit fly species unique and separate from each other had been guessed at since 1940, following experiments decades earlier in which geneticists first noticed that the two types of flies, when mated, had only daughters—no sons.
Scientists had previously discovered two other genes involved in driving the fruit fly species apart, but they knew those two genes weren’t the full story.
An original edition of Gregor Mendel’s 1866 publication, “Experiments in Plant Hybridization,” housed in NIH’s National Library of Medicine. Credit: Alisa Machalek.
This year marks the 150th anniversary of Gregor Mendel’s publication that—after sitting ignored for a few decades—helped launch the field of modern genetics. Mendel didn’t know about DNA. But after painstakingly cross-fertilizing tens of thousands of pea plants over the course of 8 years, this Austrian monk came very close to describing genes.
By picking a species with a handful of visible characteristics that occur in two easily identifiable forms, Mendel was able to pinpoint what he called “factors.” These factors determine traits like a pea’s shape or color, for instance, and are passed down from parents to offspring. He also observed that factors can be dominant or recessive.
Today, February 12, is Darwin Day—an occasion to recognize the scientific contributions of 19th-century naturalist Charles Darwin. In this video, our own evolutionary geneticist, Dan Janes, answers questions about Darwin and the role of evolution in health and biomedicine.
For more details about evolution and you, check out our articles Evolution and Health and Everyday Evolution.
Nels Elde, Ph.D. Fields: Evolutionary genetics, virology, microbiology, cell biology Works at: University of Utah, Salt Lake City When not in the lab, he’s: Gardening, supervising pets, procuring firewood Hobbies: Canoeing, skiing, participating in facial hair competitions
“I really look at my job as an adventure,” says Nels Elde. “The ability to follow your nose through different fields is what motivates me.”
Elde has used that approach to weave evolutionary genetics, bacteriology, virology, genomics and cell biology into his work. While a graduate student at the University of Chicago and postdoctoral researcher at the Fred Hutchinson Cancer Research Center in Seattle, he became interested in how interactions between pathogens (like viruses and bacteria) and their hosts (like humans) drive the evolution of both parties. He now works in Salt Lake City, where, as an avid outdoorsman, he draws inspiration from the wild landscape.
For tens of thousands of years, Neanderthals lived in Europe and Asia (presumed range shown in blue) and interbred with humans, passing on some DNA to present-day people. Credit: Ryulong, Wikimedia Commons. View larger image
Many of us have some Neanderthal genes. Before Neanderthals went extinct about 30,000 years ago, they interbred with humans living in Europe and Asia. Today’s descendants of those pairings inherited about 2 percent of their genomes from the big-brained hominids.
A research group led by David Reich at Harvard Medical School recently completed an analysis to determine the extent and identity of Neanderthal DNA in modern-day human populations. The group found that many traits in present-day people—including skin characteristics and susceptibility to various diseases—can be traced to Neanderthal DNA.
It also appears that, genetically speaking, Neanderthals and humans weren’t completely compatible. Based on the uneven distribution of Neanderthal DNA in today’s genomes, the scientists concluded that many of the male offspring of Neanderthal-human unions were infertile. In the animal world, this phenomenon is known as hybrid infertility, where the offspring of a male from one subspecies and a female from another have low or no fertility.
Studying human genes passed down through Neanderthals—as well as regions of the human genome notably devoid of Neanderthal DNA—provides an increasingly complete picture of the genetic landscape that contributed to health, disease and diversity among humans today.
Harvard Medical School News Release Reich Lab