My guess would be higher (than the average today) because it would have played a more important role in survival and spreading the genes. Low testosterone men would have less chance to reproduce. Today even the weakest and dumbest of the species can reproduce just fine (sadly).
Difficult to say. When I split wood all day my testosterone is pretty low. I assume that in midwinter, with limbs half frozen and trying desperately not to die, testosterone would have been low too. Then there would be alpha males around lowering your testosterone for you, more so than today.
Our ancestors was much higher, today they put things in our food, water, medicine, etc. to deliberately lower it to no where near what it should naturally be, testosterone leveles haven't just went to a fraction of what they were by magic.
It is very obvious that today's men are much more feminine if you see photos/films from before about 1960. It is also why they have hardly any real sex drive, poor erections, anxious, low confidence, etc.
Everyone needs to start growing their own food.
If we assert that modern hunter-gatherers would have comparable testosterone to paleolithic man, then it appears they have equivalent or lower levels of testosterone.
If we reject that assertion and assert that evolution has caused a drop in testosterone, then we may assume paleolithic man had closer testosterone to Neanderthals. I cannot find the reference right now, but I remember a study that showed Neanderthal children (as measured by some combination of bone structure and density, had higher testosterone than modern children. But there was no method of testing adults.
In my opinion (based more on thought than data), I would assume that the variance in testosterone has increased for two reasons (1) Larger variance below the average, Our society does not necessitate classical 'survival of the fittest' adaptation; (2) Larger variance above the average, We have medicinal (meds, supplements, etc) methods of raising testosterone and many people use these methods. -- However, I would doubt that the average has moved in any significant fashion.
I have certainly not studied the topic (and I'm female ) but saw this "The normal range of testosterone is reported as 350- 1200ng/dl. Studies in the 1940's showed the average testosterone level to be at 700 ng/dl, 300 ng/dl higher than for men today. In the past, a drop in testosterone levels to 250 ng/dl was rarely reported before men were 80 years of age. Yet today, it is not an uncommon value for middle aged men."
I was certainly suggested one of my son's new special underwear for cycling which looks rather tight might not be a good idea.
I have never been tested myself (women do have testosterone) but often wondered if the reason I had a reasonably high sex drive and was successful in work and like things a good few men do like money, power, ambition, beating others, success was down to higher testosterone levels than some women ( I don't have a beard by the way.....)
There seems to be a lot of variance within generations rather than between them. This article suggests that many aspects of modern living contribute to testosterone "deficiency" (bringing down the overall average), but these can be avoided by individuals: http://www.interestingarticles.com/mens-health-issues/effects-of-modern-lifestyle-on-testosterone-levels-8530.html The main culprits are (surprise, surprise): inactivity, excess weight, processed foods, stress, disrupted sleep and lack of vit D.
That said, there is likely such thing as too much testosterone also.