The problem is that increased immune vigilance has a side effect : allergies. Our speculation is that this is some kind of trade-off. In the past you needed to resist some kind of pathogen, and the trade-off or sacrifice you have to make is increased responsiveness to nonpathogenic allergens. So next time some of you get the springtime sniffles, blame your distant ancestor — the one with the heavy brow ridge.
PTELook at the text below. In 35 seconds, you must read this text aloud as naturally and clearly as possible. You have 35 seconds to read aloud.
Recorded Answer
Current status:
Beginning in 35 seconds.