Genetic Diversity

[Mr Evil 37]

It would take 'genetically' 300 people, 150 men and 150 women with each woman having between 3 to 5 children by different men for 10 generations to have a viable gene pool that is not highly prone to genetic flaws

And you know this how...?

[Girlbot]

This is assuming that all the females would be capable of reproducing the number of offspring needed, then there would be the mortality rate among the population due to the circumstances they were living under, the lack of medical facilities, etc. You can't just do math of figures alone, without factoring in other probablilites, that might decrease the gene pool IMO

[spaceship]

With 80-however many people there were on Destiny, did they really have enough people to create a stable gene pool that would last 2000 years? I remember in BSG, Baltar said that the Colonial fleet (with like 45000 people) wouldn't last nearly that long before they started having problems, so the question just kind of popped into my head. Any thoughts?

The problem in BSG wasn't genetic diversity. It was a cultural thing. People weren't having enough children. The birth rate was too low compared to the death rate. That is why they started encouraging child bearing.

[Perelandra]

I don't think it would that much of an issue given the diversity of the original population

I don't know about genetics, but I agree with this.

ETA: I didn't find a large civilization stemming from 80 or so original people to be a stretch at all.
And there is already genetic diversity on the Destiny, no one is related, so no first cousins, marrying, ect.
(What I found more of a stretch was people still speaking the same English that the founders, spoke, but a minor quibble.)

[Quetzocoetl]

I don't know about genetics, but I agree with this.

ETA: I didn't find a large civilization stemming from 80 or so original people to be a stretch at all.
And there is already genetic diversity on the Destiny, no one is related, so no first cousins, marrying, ect.
(What I found more of a stretch was people still speaking the same English that the founders, spoke, but a minor quibble.)

Agreed.
Though...I figured the whole English thing was because they had easy access to spoken English via the Kinos.

[Trinary]

Ancestor with Kino. This alone could explode into similar flying devices and vehicles. It's strange what they had only Kino's memory storage technology with them after 2000 years?

The colony should at least has cubical camp site that they could carry through gate travel. Off course, could be loaded on top of flying SUV. An equivalent to small convertible puddle jumper.

[Perelandra]

Agreed.
Though...I figured the whole English thing was because they had easy access to spoken English via the Kinos.

yes, I think you're right, now that I think about it.

[knowles2]

Ancestor with Kino. This alone could explode into similar flying devices and vehicles. It's strange what they had only Kino's memory storage technology with them after 2000 years?

The colony should at least has cubical camp site that they could carry through gate travel. Off course, could be loaded on top of flying SUV. An equivalent to small convertible puddle jumper.

May be they did. We do not know how long they spent on the planet before they cut off.

An it might be that they cannibalise there most advance pieces of technology to keep the power generators and radio communication equipment going.

[zainea13]

It would be possible, but the show made it seem like it was 'whoever can have kids with whoever' ... But it would have to be strict. One man for instance might have to seed 3 generations. So yes like a 80 year old man have sex with a 16 or 18 year old woman for the sake of genetic diversity.

Once they get to everyone being a second cousin or beyond, genetic disease should be limited if not eradicated.

[Geral]

You underestimate the power of the genome.
Having your third cousins children is 100% within acceptable genetic norms.

Populations can spring forth from much fewer specimens then you can think.
The Galapagos Islands have a diverse population of tortoises.
No more then 10 females are the parents to every single one of the 10+ species of tortoises you can find on the different islands. They have been there for millions of years.
Human genome is a little more complicated and would require a slightly more diversified genetic profile. Once you reach thousands tho, genetic diversity would not be an issue ever again.

^500 people would be like 4th or 5th generation, clearing that 3rd cousin stuff too^

Interesting episode!

Exactly. I think people underestimate 'stable gene pools'. They could breed with first, second, third cousins and as long as they keep some knowledge of genetic abnormalities I see no reason why they couldn't do it. With 60-100 or so people, I think it would be plenty of diversity to do it (though they'd still suffer from our genetic ailments). The problem occurs with far less than that, a dozen or so, that dangerous conditions become more statistically likely.

[carmencatalina]

Finally, a topic on which I can speak intelligently!

I'm a population geneticist, this is what I'm actually teaching this semester.

As several people have pointed out, one of the questions is the relative proportions of males and females. Biologists use a term called "effective population size" to measure how much genetic diversity a population will likely maintain over time.

For a population that has Nm males and Nf females (where Nm and Nf are integers representing the actual number of males and females), the effective population size is:

Ne = 4*Nm*Nf/(Nm + Nf)

So let's say that there are 20 women and 40 men aboard the Destiny.

The effective population size is only: 4(20)(40)/(20+40) = 3200/60 = 53.33

This is less than the actual population size of 60, because each new person receives 1/2 of his/her genes from a female and half from a male - the smaller number of females forms its own "bottleneck".

This assumes everyone is equally likely to reproduce - the effective population size will be smaller if there are some individuals that reproduce more than others.

But let's take an effective population size of about 50 as our estimate. Is that big enough to found a human population for the long term?

It is if the founding population is genetically diverse enough, so that it is unlikely that any two people are carrying the same recessive deleterious mutations. We all have some recessive deleterious mutations - most of the time, the person with whom we reproduce has different ones, and then our offspring don't get 2 copies of a deleterious gene at the same locus (gene). That's why many (but not all) organisms avoid close inbreeding.

The current theory of human population expansion out of Africa poses multiple small groups founding population in Europe and Asia. It is certainly likely that some of these groups had less than 100 breeding individuals. Could they have persisted without later influxes of people and genes from other groups?

I think the answer is "maybe". Certainly, we have seen populations of other mammals survive bottlenecks much more severe than 50 breeding individuals.

[knowles2]

Rhinos are one species that have been bought back from very low numbers, some species as low as fifty I believe. An they are accepting to do the same with the last 7 remaining Northern White Rhino.
But some mammals have got a natural resistance to inbreeding, cats for instant.
carmencatalina may be you should give the SGU scenario as an assignment for your students to answer whether the population on destiny is viable or not.

[g.o.d]

actually you don't need more than 60 people to start a civilisation. Of course, there must be more females than males, but it's fine to begin with less than 60 (56 to be more accurate). Some of descendants would be "slower" but you don't high numbers.

[carmencatalina]

carmencatalina may be you should give the SGU scenario as an assignment for your students to answer whether the population on destiny is viable or not.

I would need to make some assumption on the frequency of deleterious mutations in the initial Destiny population, and on how genetically related they are. If you throw in that information (that we don't have), you could do some fun calculations.

Excellent idea for a homework problem!

[Trinary]

I believe in a single gene could mutated into different races if they spread into different geographical area in a planet or the variation how they live their life. The surrounding area most likely contribute how they evolve and adapt to the place they live in. It will resulting into a different skin color, shape of the eyes, their height and various other changes.

For example, a number of a fat human race are now increasing around the world based on what and how they eat such as similar food menu and frequency. They're basically a new human race that evolve drive by the food they had consumed. They used to be abnormal, but now it was seem common a new born overweight baby taken these new evolved gene.