How Sexual Promiscuity Lost Its Evolutionary Luster
There was a time when violence and hierarchy determined who was sleeping with who, but that was before women collectively decided that security was preferable to fertility.
What's the Latest Development?
A new theory is forming to help explain why human relationships evolved from promoting sexual promiscuity to today's pair-bonding. Long ago, when violence and hierarchy determined who slept with who, females were naturally more promiscuous, habitually taking on more men than today's domesticated partnerships allow. University of Tennessee-Knoxville professor Sergey Gavrilets argues that the rise of pair-bonding "occurred only when lesser male hominids, realizing their physical inferiority, adopted a 'provider' role in partnerships, and female hominids, in turn, began to show fidelity to these partners."
What's the Big Idea?
Scientists have long debated the origins of pair-bonding because, according to evolutionary logic in which life tends to prefer greater genetic diversity and higher fertility, it never should have occurred. But females may have been instrumental in this change, choosing to prefer the security of a provider mate over the risk of lower fertility. "Critically, Gavrilets notes, this process begins with the weakest males...because they stand to gain the most from an alternative strategy like provisioning. Slowly, the strategy works its way up the dominance hierarchy, as females begin to reward the weaker males with their fidelity. Out of this sexual revolution comes self-domestication."
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Here's the science of black holes, from supermassive monsters to ones the size of ping-pong balls.
- There's more than one way to make a black hole, says NASA's Michelle Thaller. They're not always formed from dead stars. For example, there are teeny tiny black holes all around us, the result of high-energy cosmic rays slamming into our atmosphere with enough force to cram matter together so densely that no light can escape.
- CERN is trying to create artificial black holes right now, but don't worry, it's not dangerous. Scientists there are attempting to smash two particles together with such intensity that it creates a black hole that would live for just a millionth of a second.
- Thaller uses a brilliant analogy involving a rubber sheet, a marble, and an elephant to explain why different black holes have varying densities. Watch and learn!
- Bonus fact: If the Earth became a black hole, it would be crushed to the size of a ping-pong ball.
Military recruits are supposed to be assessed to see whether they're fit for service. What happens when they're not?
- During the Vietnam War, Robert McNamara began a program called Project 100,000.
- The program brought over 300,000 men to Vietnam who failed to meet minimum criteria for military service, both physically and mentally.
- Project 100,000 recruits were killed in disproportionate numbers and fared worse after their military service than their civilian peers, making the program one of the biggest—and possibly cruelest—mistakes of the Vietnam War.
In a breakthrough for nuclear fusion research, scientists at China's Experimental Advanced Superconducting Tokamak (EAST) reactor have produced temperatures necessary for nuclear fusion on Earth.
- The EAST reactor was able to heat hydrogen to temperatures exceeding 100 million degrees Celsius.
- Nuclear fusion could someday provide the planet with a virtually limitless supply of clean energy.
- Still, scientists have many other obstacles to pass before fusion technology becomes a viable energy source.
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