Complete hairlessness in men?

How does it happen that some people are apparently completely and absolutely hairless?

An acquaintence is, nearly as I can tell, completely hairless. No scalp hair, eyebrows, eyelashes, ear hair, nose hair, hair on the backs of his hands or poking out of his collar. No peach fuzz in the sunlight. No 5 o’clock shadow. No stubble from shaving or plucking or breaking of the hair shafts. At least from a foot or two away, I have never seen the slightest trace of even a single hair in the several years I’ve known him (not that I’ve seen him in anything less than street clothes).

He seems physically normal and in fine health, as far as I know. A bright, vigorous, friendly, handsome, splendid and happy fellow. I guess he’s late 30’s or so in age, though it turns out I use hair more than I realized in guessing age so hard to tell.

It’s got me wondering what human conditions can leave one without any visible hair. I’m more curious about hairlessness as a general topic, not really trying to figure out his situation in particular - which I haven’t any business knowing, anyway.

Can anyone enlighten me?

Famous British swimmer Duncan Goodhew had Alopecia universalis, reportedly as a result of a fall when he was 10.

a guy I know lost all his hair everywhere after being thrown out of the sunroof of a rolling car doing a very high rate of speed.

mrAru has alopecia. He claims he misses his nose hairs the most.

What?

They filter the dust and yuck out of the air, and keeps you from getting sick as much, or sneezing lots [from dust and whatever]

That’s weird. I get alopecia areata every so often, with years in between outbreaks. I’ve never heard of it being caused by an injury though. I thought it was strictly an auto-immune disorder.

I went to high school with a guy that had this, too. out of all our anecdata, that’s all men. it does seem weird to me, too, that it’d be caused by trauma. but you never know, the human body is strange.

A friend of mine developed alopecia in his late twenties. At one point he lost all of his hair. Losing his eyebrows gave him an unnerving appearance, but they’ve since grown back. He says his condition is an advantage because he saves the time of shaving and the money spent on shampoo, plus it makes him more memorable to business contacts.

Unfortunately, his daughter started losing patches of hair at age 4. I don’t know how her condition has developed over the last few years, though.

I’ve known one man and one woman who had it. Both were in their '60s. Both developed it as adults for no apparent reason, and it had no known effect on their health.

I just cannot imagine what about falling out of a tree would cause all one’s hair to irreversibly disappear :confused: . That is seriously bizarre.