your comments about baldness and longevity are a good illustration of one of the biggest problems in life science.

I haven't heard this particular one before, but let’s say that it comes from a simple statistical analysis of deaths. More dead bald men... so baldness means you have a reduced life expectancy? This would be a flawed argument - obviously there are going to be more deaths of bald men than not-bald men in a given year as baldness is usually a function of age. So I hope that this was not the kind of reasoning that was used (if indeed any reasoning came into the picture!)

Ok, so we'll say that we took 10 000 men of the same age and note whether they are bald today. In 10 years time we'll see how many of them died - again in 20. Does it look like there were proportionately more deaths in the bald group than the not-bald group? If so, is baldness really a factor in their death or was it a sign of something else? That's the tricky question. Obviously, if you had a cancer treatment that resulted in hair loss - or a high-stress lifestyle that caused alopecia, then the fact that you are bald has nothing to do with the underlying cause of your early death. You could find other such ‘apparent links’ for self-inflicted baldness – ‘skinheads’ dying in violent crime for example. None of these would really mean that baldness was a sign of shorter life expectancy. But it is extremely difficult to pick out the primary causes from the secondary effects.

A good current example would be the ‘link’ between cannabis use amongst young adults and the emergence of schizophrenia. Are borderline schizophrenics more likely to take cannabis or does cannabis cause or trigger schizophrenia… Looking at the statistics can give you a good idea about what might be going on, but it isn’t until you can identify a mechanism and test it experimentally that you can really tell. And much of this kind of testing would be ethically unthinkable.

i seem to recall that it was something to do with testosterone as a possible cause; bald men being better endowed with said hormone than those with full hair. that being the only real difference between the two groups.

agree that that it is rather tenuous at best but is an explanation as nobody knows why.

another "link" trying to explain why there is such an upsurge in peanut allergies was the use of peanut oil as the base for most skin creams. may be true and sounds good but nobody knows. of course it was immediately repudiated by cream manufacturers.

appendicitis is relatively rare these days but was fairly common when i was younger; again nobody knows why.

much modern nonsense is the abuse of epidemiology by anyone wanting an easy grant. and of course, these days are usually employed by someone or are funded by an industry making any results they come out with as immediately biased. it all confuses me far too much so i like to sit back and just marvel at nature.

Ah. the baldness thing - some blokes suffer from MPB (male pattern baldness) yet don't exhibit any of the other classic signs of high-level T (testosterone) i.e. they have very little body hair and low sex drive throughout adult life.

So you can't necessarily relate baldness to high T-levels.

Maybe baldies are more likely to be beaten up; maybe they get more depressed...so many variations.

p.s. I'm not having a go at bald men here, my beloved is follically challenged and I've never known him with a full head of hair but he's wonderful.

does running in shoes wear them out less quickly then walking in them for the same number of footfalls? heavens knows why i thought of that.

yep, picture with the exposure settings set correctly for a change. and a piece of luck with the jpg conversion. it's 4 or 5k i think. shows off my startling good looks, the whatyoulookingat glare and the skunk hair colouring - took hours to get all that grey put on.

is a straight pole a la hex 3 stronger than a hooped tent in wind.

would not a pole tend to oscillate with little bend as the strain of the wind is on the sides of the tent/pegs rather than on the side and hoop itself?

Parky,

I am sure that running in shoes wears them (and you) out faster than walking in them. The energy exchanges going on in running are far greater than in walking and that has to equate to additional wear and tear on the shoes.

As for the aerodynamics of single-pole tipi design, it's a interesting question. The obvious advantage of the tipi is that it is pretty much circularly symmetric so the profile is the same whatever the prevailing wind direction. And the majority of the profile is low with only a small percentage of the surface area reaching into stronger winds above ground level. Then you take a strong pole and put it in constant compression with stabilising tension of the tent fabric in all directions. I'd say this would result in a very stable shape with low risk of oscillations, especially if it is kept nice and taught.

Didn't you just buy one?

yep. just made me wonder about the design and poles and things. i have frequent flashes of the inane and inconsequential.

makes the day go faster in my involving, challenging and intellectually stimulating job. <opens an eye to see the drool on the pillow>

John

Whilst the energy exchanges will be greater when running the number of footfalls must be much smaller for a given distance. I suspect that this problem might be much more involved than it first appears.

Andybr

Andy,

I agree its a complex question... but Parky said "does running in shoes wear them out less quickly then walking in them for the same number of footfalls?" so I stick by my comments.

Interestingly, if you are running (aerobically) on the flat then the energy required to move a given distance is roughly independent of your speed. That is to say that net energy consumption depends more on gait than on speed and the the cross over in efficiency is supposed to be at about 8kmph (when it becomes more efficient to run than walk).

Some reasonable (non metric!) explanations of this are to be found in these links:

http://www.runnersworld.com/article/0,7120,s6-242-304-311-8402-0,00.html

http://www.straightdope.com/columns/050121.html

The wear on a shoe will be different depending on whether you walk or run, but the forces on a running shoe are much higher than on a walking shoe and to my mind that must equate to more rapid wear-down of the shoe.

John

"Why did early man lose most of the hair on their bodies?"

Probably it was an adaptation to aid heat loss after moving out of shaded, forest environments into scrubland and savannah. Ditto for humans having a lot more sweat glands than chimps.

 Hmmmmm, so why did not Inuits gradually  replace body body hair over many generations if their ancesters had been living in Artic situations for thousands of years?

Personally, I support the link to the "soft" humans using the artificial aid of animal skins to keep out the extremes!

(But then, why is it left in the area of the genitalia?)

Oh and Male Pattern Baldness - its just a radiator for the over sexed!

why is it left in the area of the genitalia?

The secondary sexual characteristics include pubic hair to indicate sexual maturity from a distance as an invitation for mating.

In the armpits it remains because adults sweat more than children and the hairs reduce chafing. 

The eyebrows help to prevent sweat entering and stinging the eyes. 

Very interesting NPC, so how do apes know when the opposite sex has reached sexual maturity? (and would they care)

 Doesn't the assertion that pubic hair signals sexual maturity imply that at a base level, and minus our rules of modern society, that visual signals of such sort would have mattered in early human society?

 Would they not have had the same sexual instincts as apes without the modern morality that we live by?

Oh and I meant to add that we all know what useful soup strainers moustaches are !

And another thing !

Why does the hair stop growing on a man's head and start growing instead wth a vengeance in the nostrils and ears ??