Jurassic Pouch Part I: The Invaders
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Back at the Rocket Ranch, grips unpacked, Merl, Frances, and MaryLiz settled into the settee in the dining hall. Cass crept in, followed by Varley. “We know you’re exhausted, but we have stuff to show you when you’re all centered and stuffs,” said Cass.
None of the returned travelers felt like resting, and soon they were crowded around the computer next to the magical DNA machine in the biolab.
Cass brought up a family tree, with living wallabies at the bottom. Lines indicating mother and father relationships to each offspring sprung backwards, upwards, from the living. The density of the lines indicated probability of lineage. Some of the more tenuous relationships were depicted in animated form, the computer running through combinatorial possible guesses as to an unclear lineage.
At the top of the diagram were Wallabeve and Adam-Roo, the Mitochondrial mother and Y chromosome father of every living offspring.
Cass spoke over the moving diagram. “Our original Mitrochondrial study was just to figure out mother-daughter lineages. You’ll remember that we only get our mitochondrial DNA from our mothers, and our wallabies’ most recent common n-greats grandmother was born around 1950.
“Wallab-Eve,” said Cap.
“Yes you do remember. Since we just needed basic lineage, we ran the samples through as fast as we could. Among the males (half the samples, as you’d expect), we did the same for Y-Chromosome Adam – we’re calling him ‘Adam-Roo’. You were already in Mexico by then – Y chromosomes take longer to sequence than mitochondrial.
“We didn’t need to completely sequence every single individual genome to establish probable family relationships. So we didn’t – it would have slowed things down. But since you’ve been gone….” Cass indicated the now massive stack of sample logs next to the sequencer.
“You haven’t had the boss looking over your shoulder,” said Frances, “so you’ve been able to do some actual work.”
“You betcha we have,” said Varley. There was a sparkle in Varley’s eye. “Go on, you tell ‘em,” said Cass.
“Cass’s fed me so much genetic theory that now I almost feel smart,” said Varley. “One thing we looked at was FOXP2 genes. FOXP2 is a gene that codes for a kind of protein called Forkhead Box. It’s important for brain maturation and the development of speech. Not just in our brains, but in other mammals, mice, and bats for example, and in non mammal species such as birds.”
“But those don’t talk,” said Merl.
“They actually do, after each’s fashion. Baby mice squeak for their mothers. Boy mice do it twice as often as girl mice. Guess which one has more FOXP2? Bats use echolocation, which is speech of a sort, and ordinary bird song and mimicry is driven by FOXP2.”
Varley, the fresh expert, chimed in. “Also, the gene does a lot more than just encourage the development of speech. And there’s no single gene for any trait. Traits like speech and echolocation result from the interacting effects of a host of different genes. There’s also a few different ‘flavors’ of the Forkhead Box protein. Humans have two that we share, variously, with chimpanzees and bird species. But there’s one form of FOXP2 that belongs just to us, and to no other species known to science.” The post doc nodded towards the grad student who was in this instance, the elder’s superior. It was for Cass to say what they’d found.
Cass repeated. “No other species known to science…. until now.”
Merl spoke up. “Here I was thinking I was followin’ y’all. What other species? You’re not saying the wallabies have human DNA?”
Cass blinked, and took a deep breath. “No. I’m saying that at least part of our wallaby population have a variant of FOXP2 that they share with us, and with no other known species, including our closest living ancestors on earth, the other apes. It’s either a chance mutation in the same direction – unlikely, given that the mutation only occurs in humans among all known naturally evolved species. Or –”
Frances blanched “Or it was engineered into them.”
Bender was nonplussed. “By the SOVIETS?!”
“Not a chance,” said Frances. “The science of DNA analysis was in its infancy. They knew what DNA was, but barely.”
“We agree with you,” said Cass, “And I think we can prove it.”
Frances scoffed. “Proof is for mathematicians.”
“This is mathematics. The simplest kind, just counting. The human FOXP2 variant isn’t present in every single individual, just most of them. FOXP2 travels on a different chromosome than the Y chromosome (it’s Chromosome 7 in humans), which lives in the nucleus of the cell, not the mitochondria. Between those facts, we can’t say whether Adam-roo or Wallabeve carried the human-specific FOXP2 gene. But the fact that we found living descendents with standard wallaby FOXP2 would seem to lead us to doubt either had – let’s just say it – ‘human’ FOXP2. More likely than not, the human FOXP2 mutation was added, to some wallabies and not others, about seven generations ago. A Wallaby generation can be as short as two years, and they live up to 15 years, so taking the average puts the moment about halfway back in time to Wallab-Eve and Adam-Roo. Whoever spliced them (If they spliced them!), did it decades after the fall of the Soviet Union.”
“That timeline matches the mutation being artificial,” said Stapledon. “Gene therapy was well developed by the middle of the 21st century. It wouldn’t even have been particularly expensive, once you’d committed to doing it.”
Frances was skeptical. “How does that make sense? A colony of wallabies, blown by a Cold War era hurricane from Cuba to Yucatan on rafts of storm debris. They make their way, all alone, from the Gulf Coast into the Pool of Xblanque, and then somehow… what, invent genetic engineering technology on their own? With what? Did they bring the whole shop with them? In pouches, I suppose.”
Merl hit the obvious conclusion. “They didn’t travel alone.”
“Chaperoned,” sighed Frances. “Every answer brings two more questions. Some days I wish I weren’t a scientist.”