Richard Wrangham, Catching Fire: How Cooking Made Us Human 3 million years, 120,000 generations between you and a chimp. Fruit flies are a week between generations: 120,000 generations is 2300 years. Bacteria can be 10 hours: 120,000 generations is 130 years. Ebola? 8 hours. The equivalent of "australopithecine" to "you" for the Ebola virus is 109 years. The first outbreak of Ebola Zaire was 38 years ago in 1976. On a human timescale, that was 1.6 million years ago, pretty much the endpoint of Homo Habilis: There's a whole lot of evolution to be done when your life cycle lasts 8 hours. "3 months ago" to Ebola is 14,000 years ago to humans... and while we sure looked human, and we sure acted human, and we'd sure be recognizable as human, but 14,000 years ago, North America was probably devoid of human life. TL;DR: EbolutionAlthough the australopithecines were far different from us, in the big scheme of things they lived not so long ago. Imagine going to a sporting event with sixty thousand seats around the stadium. You arrive early with your grandmother, and the two of you take the first seats. Next to your grandmother sits her grandmother, your great-great-grandmother. Next to her is your great-great-great-great-grandmother. The stadium fills with the ghosts of preceding grandmothers. An hour later the seat next to you is occupied by the last to sit down, the ancestor of you all. She nudges your elbow and you turn to find a strange nonhuman face. Beneath a low forehead and big brow-ridge, bright dark eyes surmount a massive jaw. Her long, muscular arms and short legs intimate her gymnastic climbing ability. She is your ancestor and a australopithecine, hardly a companion your grandmother can be expected to enjoy. She grabs an overhead beam and swings away over the crowd to steal some peanuts from a vendor.
She is connected to you by over three million years of rain and sun and searching for food in the rich and scary African bush. Most australopithecines eventually went extinct but her lineage slowly changed. Evolutionarily, she was one of the lucky ones.
You're right. It's strange that it hasn't changed since we encountered it in the '70s -- or has it? The lethality rate is way down from the halcyon 90 percent days, which could potentially work in the disease's advantage if it also learns to infect more efficiently. Maybe ... fuck.