What’s your opinion of your ancestors–not just the humans but your remote animal and plant ancestors as well? Mostly average, do you think? Richard Dawkins has a higher opinion.
All organisms that have ever lived—every animal and plant, all bacteria and all fungi, every creeping thing, and all readers of this book—can look back at their ancestors and make the following proud claim: Not a single one of our ancestors died in infancy. They all reached adulthood, and every single one [allowing for the inclusion of such outliers as in vitro fertilization] was capable of finding at least one heterosexual partner and of successful copulation. Not a single one of our ancestors was felled by an enemy, or by a virus, or by a misjudged footstep on a cliff edge, before bringing at least one child into the world. Thousands of our ancestors’ contemporaries fail in all these respects, but not a single solitary one of our ancestors failed in any of them.…Since all organisms inherit all their genes from their ancestors, rather than from their ancestors’ unsuccessful contemporaries, all organisms tend to possess successful genes. They have what it takes to become ancestors—and that means to survive and reproduce…That is why birds are so good at flying, fish so good at swimming, monkys so good at climbing, viruses so good at spreading. That is why we love life and love sex and love children. It is because we all, without a single exception, inherit all our genes from an unbroken line of successful ancestors. (River Out of Eden)
Dawkins goes on to emphasize that these individuals did not do anything to deserve this success; there were no noble deeds that made their way into their DNA to be passed along. It is just that the genes that produced other organisms that were less well suited to their environments were filtered out over thousands of generations, while those that were best suited to survive were, well, the ones that survived.
Dawkins paints a helpful picture of what we or any organism would see looking back millions of years at their ancestors. It’s the perspective of the “selfish genes” that have made it this far.
But what does this upbeat rhetoric overlook? What distinctions does Dawkins’ generalization prevent us from seeing?
Who, for starters, were the “failures”? According to Dawkins, they include those who died before reproducing because they were fractionally less disease-resistant or otherwise less competitive than their peers. Their early deaths represent a grim genetic sorting.
But the “failures” include another group that Dawkins doesn’t acknowledge. These were the ones who died not because their genes weren’t up to par but because of sheer bad luck. Genetically they may not have differed at all from the survivors, but they were in the wrong place at the wrong time: most of the soldiers and civilians killed in wars, victims of earthquakes, volcanic eruptions, floods, still others who went down in ships, froze in winter, starved. It’s not true, as Dawkins implies, that the failure to leave descendants confirms that an organism was genetically flawed.
And then there are the ways in which the genetic filter has not been effective enough. The passage of generations has certainly not filtered out all those ailments that are to some degree inheritable, such as certain cancers, Down Syndrome, Cystic Fibrosis, color blindness, Hemophilia and many others, as well as vulnerability to mental illness. Those who suffer from such diseases might view their biological ancestors quite differently than Dawkins does.
And the filter has no way of relieving humanity of those disturbed humans who produce offspring only to abuse them, whose children grow up to abuse their own children, who create children in the first place in order to exploit or profit from them. Those who have inherited traits that lead to violence seem to reproduce just fine.
Like the view in the rearview mirror, the view backwards along our line of ancestors helps us appreciate the long road behind us but shows only a narrow slice of the scenery.