Evolution and "childless by choice" humans...?

Question

A large part of evolutionary theory (in humans) rests on the assumption that males and females want to reproduce. These days, however, a lot of very successful people don't have any children at all.

Isn't the urge to reproduce our genes central to understanding evolution? What does it mean when people with the resources to invest heavily in children choose to have none at all?

Is the theory incomplete, or are these "successful" humans just not all that successful, Evolution-wise? Will this attitude go the way of the Dodo bird?

Answer 1

As a thought experiment, what IF all successful humans stopped having kids? The next generation, even with lack of "successful" role models, will inevitably step up and have its own successful individuals. And so on.

Does this mean that childless-by-choice people are evolutionary duds? By the conventional success by reproduction definition, sure...but consider that successful individuals also contribute a lot to society without ever adding genes. They further the knowledge base, stimulate the economy, or otherwise benefit their environment. Even though they didn't throw their genes in, they improved the quality of life for other people and (hopefully) helped to guarantee survival of the overall species.

I don't see this attitude going away in the near future. Successful people tend to have their hands too full to want to add another responsibility; many of them are also dismayed at the state of the world and don't to want to put kids out there.

The thought also occurs...what if they have siblings? Their siblings have a very similar mix of genes, and if the siblings reproduce, their dna is still (somewhat) preserved.

Answer 2

A lot?  There has to be a large change in the reproductive rate to make any kind of difference that isn't already possible do to the margin of error in even measuring such a thing.

From WHO statistics the reproductive rate in Europe has varied from .59 to as  high as 1.29 births per adult.  

(a rate of 1 would mean each adult had one child, and 1.29 is a 29% jump.)

Let's assume for a moment that  the US figures are similar (I can't find them offhand but it's unlikely they are much different, except maybe a little higher while the US sat out the first part of WWII.  But the effect would be neglible, as you'll see)

So we've got a huge range of numbers, from very negative to 29% over stability.  How many people do you think are choosing not to have kids in the US?  A million?  10 million?  50 million?

50 million is less than 17% of an approximate population of 300 million here.  Not much.

Add up the number of people in the following cities (also the top 10 or so most populated cities here)

New York City

Los Angeles

Chicago

Houston

Phoenix

Philadelphia

San Antonio

San Diego

Dallas

San Jose

Detroite

Jacksonville

Indianapolisa

San Francisco

The total is less than 30 million people.  But even if we managed to convince 50 million people not to reproduce the result would only be a 16% drop in a addition to the other people who couldn't for other reasons.  This is well withing the flucutations each year, almost an order of magnitude smaller, in a few cases.  

But it's a huge number of people.

To answer your questions:

Isn't the urge to reproduce our genes central to understanding evolution?

- I guess so.  It's certainly a basic tenet that organisms are driven to reproduce.

What does it mean when people with the resources to invest heavily in children choose to have none at all?

- It means terrible things for our population,  if enough people opt out.

Is the theory incomplete, or are these "successful" humans just not all that successful, Evolution-wise?

- it appears your research was incomplete.  Did you start with a conclusion and look for data to support it?  Regardless, there is no significant trend like the one you describe.

Will this attitude go the way of the Dodo bird?

- no.  The Dodo bird was hunted and killed for sport.  I'm not the analogy bears any close examination.  Maybe if half the population started trying to kill themselves you could apply it.

Answer 3

You could look at this from a slightly different perspective...  Success of the species depends on more than just reproduction.  We would like to believe that human society is advanced enough to appreciate that the survival of our species is at risk from things different than what they used to be.  Taking care of the environment, worrying about clean drinking water and unpolluted air and safe food supplies are all things that could have much larger impacts on the success of our species than simple reproducive success.  If humans have proven anything, it is that we can be very successful at reproducing.  There are more humans alive today than have ever lived before.  Human population is on a growth rate that can not be sustained.  It will be limited by something.  The question is will it be limited by natural forces that we can not control (plague, famine, war) or can humans be wise and powerful enough to limit our population based on what is sustainable on our little planet.

Answer 4

The percentage of these people compared to the general population is insignificant in terms of evolution.  

In other words, there are so many people who contribute to the gene pool that we are safe for the foreseeable future.

Answer 5

Not every single person or organism has to conform to the wanting to reproduce. It is entirely possible that there is a genetic mutation that has caused them to not want to have children, just like there are genetic links as to why homosexuals exist in the human race.

There are many different reasons, what with our brain being the largest and most complex in the animal kingdom.

But, no; the theory itself is not incomplete.