40,000 YEARS AGO, HUMANS PARTNERED WITH A COMPETITIVE PREDATOR SPECIES. The oldest dog fossils are ~33k years old from Belgium and Siberia, but some researchers believe we domesticated wolves about 40,000 years ago. In her wonderful book, The Invaders, Pat Shipman suggests that our alliance with wolves or "wolf-dogs" was likely a key factor in how we outcompeted Neanderthals in Europe who died out about that time. Lahtinen et al. (2021) put the domestication date closer to 29,000 years ago, and they attribute the partnership to protein. We humans can only get about 20% of our energy needs from protein, with higher percentages leading to health problems or even death. That's why we often favored the brains, marrow and other fatty portions of our kills. Wolves and dogs, on the other hand, can thrive on lean meat for months. In harsh winters, when game animals had little fat, this protein surplus led to our sharing it (probably unintentionally) and promoted the canine domestication. As this partnership progressed, friendliness in wolf-dogs was selected for, and the bonds grew ever deeper. There's even genetic evidence of this - Von Holdt at Princeton has found disruption in a genetic "friendliness" region in dogs that remains intact in wolves. Humans that have similar variations experience Williams-Beuren syndrome, a condition causing them to be exceptionally trusting and friendly. And dogs have truly become our "babies", having hijacked the human brain's maternal bonding system. When humans and dogs stare into each other's eyes, oxytocin is secreted, exactly as it happens between human mothers and their babies. It's the only certain case of this happening between different species. SO AMAZING!