Liberal Arts Blog — “Hidden in Darkness” (Darwin) — the Real Origins of Sex

Liberal Arts Blog — Wednesday is the Joy of Science, Engineering, and Technology Day

Today’s Topic — “Hidden in Darkness” (Darwin) — the Real Origins of Sex

So when did this whole sex thing start? For Charles Darwin it was a mystery “hidden in darkness.” Today, first, the remote origins of sex. Second, the case against sex. Third, why sex triumphed. This is a summary of an article on the BBC website on this intriguing topic. Experts — please chime in. Correct, elaborate, elucidate.

THE OLDEST FOSSIL RECORD: 1.2 billion years

1. “It was seaweed that first had sex.”

2. The first evidence of differentiated male and female reproductive cells was in the species “bangiomorphus pubescens,” a form of red algae.

3. “Today we know that red algae lack sperm that actively swim. They rely on water currents to transport their reproductive cells, which is likely how they have been doing it for the last 1.2 billion years.”

NB: Did environmental change play a role in the appearance of sex? Some think so. The fossils of bangiomorphus pubescens appeared just when “hundreds of millions of years of relative environmental stasis had come to an end. We see major perturbations in the carbon and oxygen cycles at this time.”

THE CASE AGAINST SEX

1. “The mechanism of asexual reproduction is much more efficient and less messy than sexual reproduction.”

2. An asexual species does not have to waste time and energy searching for and impressing a partner, they just grow and divide in two.”

3. “Contrast that with the troublesome, and sometimes dangerous, process of attracting a mate for sexual reproduction.”

NB: “And then there are the other obvious costs of sex. Joining together chunks of two separate genomes requires a different kind of process — an egg must be fertilized. It also means each parent only passes half of its genes to the offspring. Asexual parents, in contrast, produce offspring that are basically carbon copies of themselves, which sounds like a better approach for a world in which we are told that our genes selfishly want to guarantee their survival.”

THE TRIUMPH OF SEX — the “learning analogy”

1. “Evolution is about “information preservation and information acquisition — the more you know the better you are,”

2. “An organism “learns” new information, especially in a changing environment, and the organism passes those lessons on (in its DNA) to the next generation to help them survive.”

3. “Sex allows this to happen more efficiently, offering an easier way for species to “remember” useful information — it is coded in their genes. This is because the process involves choosing a sexual partner that has, itself, reached sexual maturity by making good choices. Sex means choosing a good partner and therefore choosing a better future for your offspring.”

NB: “It is vital for males to compete for reproduction and females to choose between competing males. Sexual selection through the existence of two sexes maintains population health and protection against extinction.” Is this really true? Is this fair?

http://www.bbc.com/earth/story/20160704-the-real-reasons-why-we-have-sex

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YOUR TURN

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