h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The points made were not that homo erectus had a larger head, but the reverse. The issue of sexual selection was also raised, it is hard to imagine a female homo sapien selecting a homo erectus as a mating partner due to physical and suspected intellectual differences.

<>

You don't have to go back that far for evidence of "inbreeding".

Each of us has 2 parents. Each of them has 2 parents giving us 4 grandparents. Each of them has 2 parents, giving us 8 great-grandparents.

So, each generation you go back has twice as many ancestors as the last. Let's take a generation a being 25 years (some people say 30 years, others as few as 20, but 25 makes 4 generations per century and keeps the math easy to understand.)

A child born in 1966 would have

16 ancestors in the year 1866
256 ancestors in the year 1766
4,096 ancestors in the year 1666 (Great fire of London)
65,536 ancestors in the year 1566
1,048,576 ancestors in the year 1466
16,777,216 ancestors in the year 1366
268,435,456 ancestors in the year 1266
4,294,967,296 ancestors in the year 1166 (what was the population of the world in 1166?)
and a staggering 68,719,476,736 ancestors in the year 1066 (Norman Conquest of England)

So we all have more than a little inbreeding in our family trees.

An amusing aside: If you ever meet someone who claims to be able to trace their ancestors back to the Norman Conquest, just ask them "What, ALL of them?" and see what they say...

Yes, but this theory relies on all those people to be able to pair with someone from outside that family, doesn't it? or are you allowed to "in-breed" if you're a distant enough relative?

What i'm really asking is, how many different people does this require to start the theory - just 2? I think not.

<>

Not only is in-breeding allowed, it is compulsory. The point of my earlier post is that in much less than 1000 years your ancestors exceed the total human population on Earth. Try taking it back a million years (40,000 generations) and see how many ancestors you would have had alive then!

Of course the same individuals must keep repeating along that line of your family tree.

I suspect that some of the pairings in our family trees (and let's face it - the numbers suggest that we must almost certainly all be distantly related) probably aren't as distant as we might like.

Now doesn't that raise some interesting questions?

Who's been sleeping in my porridge?

Okay, please explain why in-breeding is compulsory?

<>

Because, beyond a certain point in your ancestry you will have more living ancestors at any time than the total number of people on Earth.

so we really are all brothers and sisters!!!!

scary.

Well, cousins anyway.

i love it when i meet long-lost relatives!

No. This does not refer to the Garden of Eden. The scientists were being cutesy. When atheists say "Oh my God!" it doesn't mean they really have a God. Here, just read this excellent website: http://www.talkorigins.org/faqs/homs/mitoeve.html

40,000 years ago when we had most ancestors than the population of the planet there was no organised religion stating that a person can only have one partner for life. Male promiscurity was not a problem but a way of promoting genetic diversity within the population. The "four year itch" that some females experience today is a similar mechinism with the addition that the child of such a coupling would be a toddler by the time their mother had found a new man. The timeline is 1-6 months conception occurs, 10-15 months the child is born, 30 months the child begins to walk and becomes the responsibility of the tribe, 48 months the child begins learning skills from adults other than their parents.

<>

This may well be true. However, we had more ancestors than the population of the planet a mere 1000 years ago. I am pretty sure that there were a couple of "organised religions" about at that time.

At least one of these stated that a person should only have one partner for life. How many of the adherents to this religion complied with this restriction is another matter!

This is a very western sentiment. Only when "White Men" came into contact with other societies did the idea of monogamy transfer across cultures.

Also you have not yet explained the internal wiring responsible for male promiscuity or the female four year itch away.