The Irish Examinier posts, ‘Don’t freak out, but scientists think octopuses ‘might be aliens’ after DNA study.‘ I guess this is just an eye-catching title to bring in readers for a pretty straight-forward article about how octopi are different from other animals. This article is referring to new data published in Nature following DNA analysis of the octopus, Octopus bimaculoides.
Octopi can escape confinements, like this one that was sealed inside a jar with a screwcap:
They can move over land as well as in the water (especially when motivated by food):
They can mimic other animals:
And use camouflage to hide:
Briefly, though, I would like to take a second to look critically at the basic claim – not because it’s realistic, but because it’s useful to think about what we would or wouldn’t expect to find in a real alien.
claim: “octopus DNA is highly rearranged – like cards shuffled and reshuffled in a pack – containing numerous so-called “jumping genes” that can leap around the genome. ”
answer: it’s interesting that their DNA is rearranged in ways that we don’t see in other species, but it’s still DNA, right? And it still follows the same ‘universal codon’ rules dictating what codons (3 letter nucleotide sequences) call for what amino acids. That all life uses the same DNA and rules for its use is one of the most convincing pieces of evidence that all life on earth is related to one another.
claim: Octopi have “eight prehensile arms, [a] large brain and … clever problem-solving abilities”
answer: This all just makes them interesting specimens, not alien. Albert Einstein was extraordinarily smart and was not caught up in group-think (at least early in his career). This made his a great scientist, not an extraterrestrial.
claim: “Analysis of 12 different tissues revealed hundreds of octopus-specific genes found in no other animal, many of them highly active in structures such as the brain, skin and suckers. ”
answer: This is actually great evidence of a large gap between octopi and other organisms, perhaps even stumbling upon new genes or gene combinations that allowed them to rapidly evolve away from homologies with their closest phylogenetic neighbors. Perhaps this phylogenetic tree might be hinting at such a separation for mollusks?
claim: “Hox genes – which control body plan development – cluster together in almost all animals but are scattered throughout the octopus genome. ”
answer: Pretty cool. But I’ve always wondered what kept these genes together in other animals rather than why are they scattered in the octopus. Difference is always intriguing though, so I get why this is notable. from the paper that elicited the Irish Examiner article, Albertin, et al, comes this cartoon of the arrangement of hox genes in other species compared to the scattering across several chromosomes in octopi:
Rather than call them aliens, which I agree might grab the interest of Discovery Channel viewers, I prefer Albertin, et al’s description, “Our analysis suggests that substantial expansion of a handful of gene families, along with extensive remodelling of genome linkage and repetitive content, played a critical role in the evolution of cephalopod morphological innovations, including their large and complex nervous systems.”
August 18, 2015 at 6:58 am
Good thought for my day. I will be sitting thru lecture thinking about Octopi…… god give me strength to focus today.