Humans today are mosaics, our genomes rich tapestries of interwoven ancestries. With every fossil discovered, with every DNA analysis performed, the story gets more complex: We, the sole survivors of the genus Homo, harbor genetic fragments from other closely related but long-extinct lineages. Modern humans are the products of a sprawling history of shifts and dispersals, separations and reunions—a history characterized by far more diversity, movement and mixture than seemed imaginable a mere decade ago.

Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.

But it’s one thing to say that Neanderthals interbred with the ancestors of modern Europeans, or that the recently discovered Denisovans interbred with some older mystery group, or that they all interbred with each other. It’s another to provide concrete details about when and where those couplings occurred. “We’ve got this picture where these events are happening all over the place,” said Aylwyn Scally, an evolutionary geneticist at the University of Cambridge. “But it’s very hard for us to pin down any particular single event and say, yeah, we’re really confident that that one happened — unless we have ancient DNA.”

The answer to halting triple-negative breast cancer, the deadliest of all breast cancers, may have just been discovered by researchers from Boston Children’s Hospital.

A CRISPR gene-editing system — all encompassed into a nanogel capsule, that is then injected into the affected person’s body — is the potential antidote to stopping the growth of triple-negative breast cancer tumors.

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Scientists have produced and tested, in mice, a vaccine that protects against a worrisome superbug: a hypervirulent form of the bacteria Klebsiella pneumoniae. And they’ve done so by genetically manipulating a harmless form of E. coli, report researchers at Washington University School of Medicine in St. Louis and VaxNewMo, a St. Louis-based startup.

Klebsiella pneumoniae causes a variety of infections including rare but life-threatening liver, respiratory tract, bloodstream and other infections. Little is known about how exactly people become infected, and the bacteria are unusually adept at acquiring resistance to antibiotics. The prototype vaccine, details of which are published online Aug. 27 in Proceedings of the National Academy of Sciences, may offer a way to protect people against a lethal infection that is hard to prevent and treat.

“For a long time, Klebsiella was primarily an issue in the hospital setting, so even though drug resistance was a real problem in treating these infections, the impact on the public was limited,” said co-author David A. Rosen, MD, Ph.D., an assistant professor of pediatrics and of molecular microbiology at Washington University. “But now we’re seeing Klebsiella strains that are virulent enough to cause death or severe disease in healthy people in the community. And in the past five years, the really resistant bugs and the really virulent bugs have begun to merge so we’re beginning to see drug-resistant, hypervirulent strains. And that’s very scary.”