The Bizarre Science of Life-Moves-to-Land Stories
Adhering to the two key evolutionary principles of i) all life sharing a common ancestor and ii) life beginning in the sea, leads to the conclusion that all terrestrial life emerged from the sea. Leaving aside the need to explain how the arrival of land-based plants, these foundational evolutionary principles raise the questions of when and how all terrestrial creatures derived from sea life.
In Richard Dawkins’ account of the evolution of land-based life numerous creatures emerged from the sea and turned into all terrestrial life. Dawkins claims, “If you go back far enough, everything lived in the sea – watery, salty alma mater of all life. At various points in evolutionary history, enterprising individuals from many different animal groups moved out on to the land...In addition to the reptiles, birds, mammals and insects we see all around us, other groups that have succeeded in making the great trek out of life’s watery womb include scorpions, snails, crustaceans such as woodlice and land crabs, millipedes and centipedes, spiders and their kin and at least three phyla of worms,” (Dawkins 2009: 161). Within this scheme the prevailing evolutionary view expounded by Dawkins and others is that lobe-finned fish became amphibious and then amphibians became mammals. Professor of Ecology and Evolution at the University of Chicago, Jerry Coyne argues that the earliest “four-legged animals...were lobe-finned fish,” (Coyne 2009: 28). Dawkins claims, “It is from the ranks of the lobe-finned fishes that we sprang,” (Dawkins 2009: 162-3). There doesn’t seem to be much explanation of how creatures other than fish left the sea, but in Dawkins’ and Coyne’s accounts a fish became amphibious and developed lungs enabling life to move on to land.
There are numerous logistical problems with the hypothetical process of fish becoming mammals, such as fins becoming legs, gills becoming lungs and reproduction changing from thousands of eggs to just one. Some creatures, such as mudskippers and Tiktaalik, (Attenborough, Kaplan and Young 2010: 251-256) show amphibious characteristics but, as Harris and Zarcinas point out, “when fish are stranded on shore they suffocate and die quickly; they do not start mutating various options for breathing air,” (Harris and Zarcinas 2014: 225).
Confusingly, Attenborough, Kaplan and Young state that creatures migrated from sea to land, but then give an account of fresh-water creatures moving on to land. “Once plants made the move onto land,” they argue, “both food and territory...became available on the continents,” and, “this was attractive to plant-eating animals in competitive marine [ocean]environments,” (Attenborough, Kaplan and Young 2010: 250). However, the narrative switches from “animals in the oceans,” (250) to, “lake and pond-dwelling animals,” surrounded by “rotting tissues of plants” which, “added to the evolutionary pressures that pushed some animals onto land,” (Attenborough, Kaplan and Young 2010: 254). Moving the scene from oceans to ponds side steps the problem of salt water amphibians, since, “Amphibians are essentially freshwater creatures,” (Harris and Zarcinas 2014: 232).
Attenborough, Kaplan and Young imagine a scenario where larger fish (rhipidistians) repeatedly chase small fish into the shallows and evolve, “a mechanism for pushing [themselves] off the ground when chasing prey in shallow water,” so they can become, “better hunters.” The authors speculate that there was a lack of oxygen so the rhipidistians “found a way to mange,” by acquiring “nostrils” and, “connecting their nostrils with their mouths.” Bill Bryson highlights the matter that, “to live on land, creatures had to...develop a way to take...oxygen directly from the air rather than filter it from water,” (Bryson 2004: 410). But fish don’t have lungs so it remains a mystery, “where and how this air was being processed,” (Attenborough, Kaplan and Young 2010: 254).
Harris and Zarcinas make the point that, “if Evolutionary Theory is correct, there should be one simple biological path to follow. However what is actually presented is a variety of options, which are all still only theories, not facts,” (Harris and Zarcinas 2014: 222). Bill Bryson argues that insects, rather than fish were the first creatures to make landfall, (Bryson 2004: 410). He contends, “the first visible mobile residents on dry land were probably much more like modern woodlice, sometimes known as pillbugs or sow bugs. These are the little bugs (crustaceans, in fact) that are commonly thrown into confusion when you upturn a rock or log,” (Bryson 2004: 411). Harris and Zarcinas offer another account where, “the first creatures... to live both on land and in water were the eurypterids, which were arthropods with external skeletons and looked like scorpions,” (Harris and Zarcinas 2014: 223). They touch on the theory that molluscs had a separate evolutionary route from land to water, (Harris and Zarcinas 2014: 237,239).
Attenborough, Kaplan and Young also propose that an insect-like bug may have been the first creature to move from water to land. The authors suggest that a fossil found in Scotland in 2004 of a 1 cm long millipede could represent the oldest-known land animal. The millipede appears to have had breathing holes (“spiracles”) which indicate, along with its legs, that it was living on land. The authors speculate about the transition of the millipede to land from living in the sea. The idea is proposed that competition for food led some millipedes to venture out on to land to eat vegetation and the ability to survive on land became encoded in their genes. The authors speculate that hunting millipedes could be a reason rhipidistians migrated onto land, (Attenborough, Kaplan and Young 2010: 256).
Another suggestion by Attenborough, Kaplan and Young is that some unknown creature moved from land to water before the millipede. Fossilised animal tracks were found in rocks dated at an earlier period than the millipede fossil, but because no fossils were found of the creature concerned the find has not been accepted as conclusive evidence of earlier forms of land-based life. Because the tracks were dated so long ago in the evolutionary timescale, the animals making them would have been on land before there were any plants. The authors speculate that creatures may have come onto land to lay eggs in a safe place, away from predators, (Attenborough, Kaplan and Young 2010: 260).
Prothero’s evolutionary tree time line shows a “soft-bodied” animal shaped like a doughnut that was the supposed ancestor of trilobites fish and amphibians, (Prothero 2007: 1). According to Prothero’s diagram insects and spiders evolved from trilobites. Prothero give a detailed account of how amphibians evolved from fish (2007: 216-231). In this account lobe-finned fish use their fins to move about on land and eventually develop limbs. The presentation juxtaposes a ‘rhipidistian’ like Eusthenopteron with an Ichthyostega inferring “evolutionary modifications” from the former to the latter (Prothero 2007: 225). However, as Jonathan Wells points out, “With two different, ancient, extinct species – often far removed from each other in time and space – there would be no way to demonstrate and ancestor-descendant relationship,” (Wells 2017: 31). This is what Prothero does, tracing a “transitional series from ‘rhipidistians’ through primitive tetrapods,” to amphibians and humans, (2007: 226). The series is accompanied by another diagram showing the “transformation of the pectoral fin of lobe-fins into the hand and forelimb of primitive tetrapods,” (2007: 227) which again juxtaposes fossil skeletons to create the impression of a sequence, bringing in Tiktaalik as “the clinching piece of evidence” (2007: 228). The focus is on the fish-to-amphibian route from water to land because a story can be formed from the evidence. However, there is no treatment of the means by which other creatures and forms of life are supposed to have migrated from water to land. Without diverging from the evolutionary principle of a universal common ancestor (LUCA, last universal common ancestor) there are two options. Either at least two forms of life migrated from water to land and there then needs to be at least one other account besides fish-to-amphibian, or fish-to-amphibian is the only way life moved from water to land, and we are left with the bizarre prospect of a fish evolving into a bee, an ant, a giraffe and a butterfly. As Harris and Zarcinas put it, “effectively a fish mutated to become a snake, a mosquito, a dinosaur, an ant, a bird, a human, and every other living creature,” (Harris and Zarcinas 2014: 221-222). Harris and Zarcinas identify some of the problems facing an account of fish becoming amphibious, such as developing legs and lungs (Harris and Zarcinas 2014: 226-233). They deal with the point that this process must all be ‘blind’ accidental mutations without awareness of purpose (226) which would lead to bizarre phenomena such as one-legged fish (230). However, they do not follow the development of insects from fish, stating that, “it has been thought by many evolutionists that a possible ancestor to insects may have been a legless worm-like creature that came out of the water. No evidence of such as being has ever been found nor is there any suggestion that this creature is also the ancestor to other invertebrates,” (Harris and Zarcinas 2014: 239). While Dawkins and others may take the view that “many different animal groups moved out [of water] on to the land,” (Dawkins 2009: 161), this means likewise many credible accounts are required of transitions from water to land, and these are so far lacking.
Attenborough, D., Kaplan, M. & Young, J. First Life London: Harper Collins/BBC 2010
Bryson, B.(2004) A Short History of Nearly Everything London: Black Swan
Coyne, J. A. (2009) Why Evolution is True Oxford: OUP
Dawkins, R. (2009) The Greatest Show on Earth: The Evidence for Evolution London:Bantam
Harris, R. & Zarcinas, S. (2014) Evolution Unraveled: How Science Disproves Evolution Glenside, Australia: Starmonics
Prothero, D. R. (2007) What the Fossils Say and Why it Matters New York: Columbia University Press
Wells, J. (2017) Zombie Science: More Icons of Evolution Seattle: Discovery Institute