You have probably had the feeling before. Your running shoes are pounding the pavement — then suddenly your pain fades away, and you are feeling euphoric. The runner’s high.
That biological perk, however, may be limited to mammals that evolved for endurance exercise — like us. So says a study in the Journal of Experimental Biology.
Researchers had humans and dogs — both natural-born runners — jog a half hour on a treadmill. Then they sampled their blood for endocannabinoids, some of the compounds thought to trigger the runner’s high.
As expected, humans and dogs had much higher levels after the run. But when sedentary ferrets took the same 30-minute trot, they had no spike in those feel-good molecules.
The authors have ferreted out the reason, saying it was because long-distance running could have helped our hunter-gatherer ancestors find more food, thus increasing their reproductive success, and they speculate that natural selection may have linked up a feel-good reward to that beneficial behavior.
These days, of course, this ancient trait will not help us find extra calories, but it may encourage us to run them off.
1. fade away v. phr.
逐漸消失、衰弱 (zhu2 jian4 xiao1 shi1, shuai1 ruo4)
例: Our parents are fading away as they get older.
2. perk n.
振奮 (zhen4 fen4)
例: I felt a sudden perk after drinking three cups of coffee.
3. ferret out v. phr.
查出 (cha2 chu1)
例: It will take years to ferret out the truth.