My sister the sponge. Your sister the sponge, too. Modern genetic analysis has concluded that the extant evolutionary sister to all animals is the sponge. The former contender for the title of sister to us all is the comb jelly. Comb jellies look like jellyfish, and are far more sophisticated than sponges. Sponges sit on an ocean or freshwater body floor and filter-feed. Comb jellies propel themselves through water, have a rudimentary nervous system and gut, and create patterns of light—they’re pretty. Comb jellies are active predators. Evolutionary scientists argue that going from the comb jelly to the sponge is going backward in terms of features, and therefore backward in evolution (a rudimentary explanation if ever there was one, and all mine).
What is an evolutionary sister to all animals? She is the first one to branch out from THE common ancestor to us all. The common tree started with the common ancestor, and branched from there, throwing out the sponges as the maiden sisters to us all.
Sponges don’t travel and they don’t wear pants, square or otherwise
Why sister and not brother? Sister-brother would be more correct. Most sponges are male and female, and have the ability to play either role in their sexual reproduction. Sponges also are able to reproduce asexually by breaking off a piece of themselves. The bud falls and clings to a solid and grows into another sponge. Although sponges don’t travel, there’s a lot going on —some are even carnivorous, capable of eating the hapless small crustaceans that blunder inside.
My sister, the sponge
A sponge is an amazing animal in a stolid sort of way, but she is not the sister I’d hoped for as a child. I didn’t prefer a sister over a brother when I was a child, but I wanted someone to help me with my parents, to help me with the world. Would she have? Probably, but it’s a moot point. The older I get, the more I think that children without siblings miss insight into others. It has taken me a long time to understand that I don’t know how someone else feels or thinks about a situation, and that I should not assume that they feel as I do. Of course, I do make assumptions, still.
The simple “walk a mile in my shoes” type of thing is so important in life. It’s not to say that all people with siblings understand others, can walk in their shoes—Donald Trump comes to mind—nor is it correct to think that all only children can’t understand others. It is true that it might have helped me as a child and as a young person to know another child so well that I could understand the inner workings of a human a bit better. Other children were basically strangers to me, no matter how many hours I spent in their houses, embedded in their families temporarily.
My sister sits a lot
If the sponge branched out from the bottom of our ancestral tree, she just sat there, at the bottom. She sat while fish walked out of water, dinosaurs came and went—except the feathered ones—and we humans lost our fur, except in the odd, silly tufts retained. Six hundred million years later, she’s sitting there still.
The oceans are changing in composition, rapidly now—will she survive the acidification of the waters by increased carbon dioxide worldwide? Boring sponges (as in drilling, not yawning) take advantage of the disastrous effects of acid on corals. These sponges break down the calcium carbonate from diseased corals and recycle it. Sponges are tough cookies. Their relative simplicity may help their survival, but vast climate change will wreak vast change in animal populations.
Now that I know that the sponge is my evolutionary sister, she seems much closer to home. I’ll worry about her.