How does the Medieval brain compare to the modern brain?

Mallignamius

Physiologically, is there much difference between the human brains of 500 to 1,000 years ago and today's brains? About when in our past would you say a minor difference in the comparison begins?

By "minor difference," I mean perhaps in overall intellectual and/or mental abilities at around 5%.

My curiosity is this: If in the next 500 to 1000 years we have little physiological difference in our brains' potential, then besides simply a lack of knowledge, what's keeping us from being intellectually/mentally advanced by as much as we will be in the future?

BillJx

I don't have any knowledge in this area, but it seems to me that the human brain hasn't changed in a long, long time. During the many thousands of years that the various peoples have been separated, there has been divergent evolution of hair characteristics, facial features, body size, metabolism, melanin, and various other characteristics. The greatest sociological discovery of the past century is that there has been no divergent evolution of intelligence or even of personality. Why that should be the case, who knows?

For the second part of your question, and still keeping in mind that I'm a complete know-nothing, future intellectual advances could come in two ways:
- correction of minor but normal imperfections of brain development and
- implants.

Since these technologies probably wouldn't be universally affordable, then the universality of human nature might no longer be true.

stickythighs

There is almost no difference between the human brains of 500 to 1,000 years ago (or even 20,000 years ago) and today's brains. If babies born 20,000 years ago were magically transported to 2008, the babies would be indistinguishable from the babies born in 2008 when they grew up.

BWV

The premise is that somehow the medievals were dumber than us, which is not the case. We simply have more knowledge and better tools.

CRGreathouse

Are there any sources for these assertions? I wouldn't be surprised if there was little change in the human brain over the last 1000 years (or even 5000 years), but I don't think it's at all obvious. I see two opposing forces at work:

1. The advantage of intelligence today is greater (I assert) than the advantage of intelligence 1000 years ago, relative to other genetic traits. All else equal, this would tend to increase average intelligence -- and could easily happen over only a few hundred years, if the change was strong enough.

2. Modern health services give better treatment for 'low-IQ' and otherwise mentally handicapped people, and legal systems have moved toward the protection of the rights of all, including people with low intelligence. In particular, their rights to life and procreation are relevant here (and I assert both have improved). All else equal, this would tend to decrease average intelligence.

Now there may be other trends in place, or these two might simply happen to cancel, or their effects might be weaker than I would expect -- but without evidence, I find neither of the following claims persuasive:
C1. Average human intelligence has not increased over the last thousand years.
C2. Average human intelligence has not decreased over the last thousand years.

Both are claimed in the posts above, but the arguments consider only C1. I would appreciate any sourcing for claims C1 or C2, for any reasonable values of "average" and "intelligence", and any timeframe within a factor of 10 (100 to 10,000 years).

mgb_phys

An advantage only has a genetic effect if it causes you to have more surviving offspring.
Today number of offspring is inversely proportional to inteligence (measured in terms of educational and job performance)

I'm stilli guessing the village idiot in the 1500s had more chance of having kids than someone in a mental health institution today.

All this assumes that 50 generations is enough to have any selective effect anyway.

CRGreathouse

So you would argue that intelligence has dropped over the last 500 years, then?

50 generations is easily enough if the factor is sufficiently strong.

mgb_phys

If it has a genetic component then it might be dropping in the future, http://us.imdb.com/title/tt0387808/

If the leaking flat roof of my lab is anything to go by it's certainly dropped in the last 500 years.

berkeman

Intriguing question. I googled brain size history (on the premise that brain size would be the main thing that has changed in the past few 1,000s to 10,000s of years), and got lots of interesting hits. Check out this one that is talking about a timeline on the order of the past 5800 years:

http://www.sciencemag.org/cgi/conten.../309/5741/1720

Moonbear

The only answer that can legitimately be provided here is, "We don't know." The sort of tools we have now to study and understand the brain were non-existent in medieval times, so there would be no records from then to use as a basis for making any comparison.

mgb_phys

http://britastro.org/baa/images/stor.../cavendish.jpg
http://www.freefoto.com/images/32/01...ngland_web.jpg

Guess which one's roof leaks!

CRGreathouse

Selection bias, anyone?

vanesch

Also, brain size (especially when it goes about small differences) is not necessarily an indicator of differences in intelligence. Neanderthal had a slightly larger brain than sapiens sapiens for instance. Just random googling: http://hypertextbook.com/facts/2001/...Shchupak.shtml and http://en.wikipedia.org/wiki/Neanderthal
Moreover, as they were smaller than we, their brain/body ratio was even bigger.

One has not found a correlation between the "intelligence" of a person and its brain size (Einstein's brain didn't have anything exceptional, anatomically speaking).

somasimple

Here are two examples of these ancient idiots =>
http://en.wikipedia.org/wiki/Archimedes
http://en.wikipedia.org/wiki/Pythagoras

Unfortunately, they are tons...

Moonbear

I'm not sure what point you're attempting to make here. What does leaky roofs have to do with physiological processes in the brain?

Also, the original question really is not asking if people were more or less intelligent (not that there's really a good objective way to even determine that), but if there are different physiological processes. That's talking about cellular level mechanisms. We certainly see individual variation in HOW people accomplish different tasks that would involve some physiological and anatomical variation without overall affecting intelligence, but we'd have no way to know if that differed in any meaningful way from people in the medieval period. It may have had nothing to do with intelligence. What if it is something like appetite regulation? People then made do with far less food than we do today, so something may differ in brains as food scarcity diminished. Or, what if it was the emotional response to loss/death that was different? The brain does a lot more than just solve problems or build roofs.

vanesch

does it ?

CRGreathouse

I can't speak for the rest of your post, but I know that there's a fairly strong (positive) correlation between g as measured and brain mass.

There's a whole website devotes to the correlates of intelligence (can't seem to Google it up right now; anyone know what I'm talking about here?) which summarizes several hundred papers, their methodologies, and their results. If I can find a link that would surely give some numbers.