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Snakes losing legs is not evolution!

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Figure 1. Heat pits on the nose area of a python (top) and a rattlesnake (bottom).

Yet another case of devolution

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Published: 7 January 2020 (GMT+10)

Introduction

Evolutionary theory describes the origin of snakes very differently than the Bible. According to the Bible, the snake was “more crafty than any other beast of the field” made by God (Genesis 3:1). In Genesis 3:14 the snake has to move on its belly after God had cursed it, meaning that snakes could possibly have had limbs before the Fall. According to evolution, snakes are an order of reptiles which are related to all other species of animals, going back millions of years.

“Evolution for Skeptics” is a blog written by evolutionary biologist Christopher Emerling, who studies genomic adaptations in vertebrates at the University of Montpellier, France. He says he believes in God. His blog seeks to presents evidence for evolution to those in the broader religious community who are skeptical about evolutionary theory, such as biblical creationists. Emerling also claims to have been exposed to creationist teachings for most of his life. Nevertheless, as this article will demonstrate, there are serious shortcomings with his ideas about how claw gene ‘remnants’ supposedly point to legs in snake ancestors. The evidence for loss of legs in snakes makes better sense according to biblical creation.

What did the researchers find?

Emerling focused on the expression patterns of genes which code for keratin. Keratin is a structural protein, which is present in hair, nails, feathers and horns. He chose keratin because two genes, HA1 and HA2, are expressed almost exclusively in the claws of lizards. The HA1 gene is functional in lizards, except for a legless species of lizard, called the slow worm (Anguis fragilis). However, even in this legless species, the HA1 gene was present, but it was non-functional.

While the HA2 gene was not found in snakes, the HA1 gene was found in six of the eight snake species studied.1 In these species the HA1 gene was also found to be pseudogenized (its sequence was broken). In all six of the snake species, the same 8 base pair long segment was found inserted in the first portion (exon) of the HA1 gene.

Besides the HA1 and HA2 genes, Emerling also noted some genes in the taste buds and also the visual system of some snakes that are either absent or degraded. These genes include the taste receptors TAS1R1, 2, and 3. Two opsin photopigment genes (RH2 and SWS2) seem to be degraded in some snakes, and three light-associated genes (OPNP, OPNPT, OPN5L2) are thought to be absent from the snake species studied by Emerling.2 The degradation/loss of these genes corresponds to differences in the structure in the lens, iris muscle and structure of the retina compared to their presumed lizard ancestors.3 The loss of these genes is thought to be associated with a transition to activity in dim light.

How similar are lizards to snakes?

Some evolutionists, including Emerling, think snakes evolved from lizards by losing their legs. Is this true? Are there not other basic anatomical differences, which differentiate lizards from snakes, beyond the presence or absence of limbs? Indeed there are.

All lizards have an eyelid as well as a nictitating membrane, which is a transparent ‘third eyelid’ that can be pulled across the eye to keep the eye moist and protect from dust, whereas snakes lack these two structures. Snakes have fangs and a flexible jaw hinge, whereas lizards have flat teeth and immobile skulls. Some snakes have heat pits on their nose but they have no external ears (figure 1). Heat pits are sensory organs around a snake’s nose which sense thermal radiation. Lizards, on the other hand, lack heat pits but have external ears.

Snakes move by gliding using the bottom scales on their body. Lizards move by either twisting their stiff body or by using their legs. The tails of snakes are short and do not break off when grabbed. In contrast, lizards have longer tails that may break if another animal grabs it.4 These differences are listed in Table 1. This means that it is unlikely that snakes would have devolved from legless lizards, because lizards and snakes belong to different kinds of animals.5,6 In other words, the evolutionary narrative that snakes inherited degraded genes from lizards is false.

Table 1. Main anatomical differences between snakes and lizards

Characteristic Snakes Lizards
Eyelids no eyelids eyelids present
Nictitating membrane absent present
Teeth fangs (sometimes hollow) flat teeth
Jaw flexible immobile
Locomotion gliding on bottom scales twisting body and legs
Tails short, do not break off long, can break off
Sensory organs heat pits (many species); no ears external ears

What is the real origin of snakes?

Table 2 lists several species of fossil snakes, together with their estimated evolutionary age, as well as a note specifying whether they had limbs or not. Four snake species with an estimated evolutionary age ranging between 167 and 140 million years are all limbless, whereas evolutionary younger snakes have been found with hindlimbs, with the exception of Xiaophis myanmarensis.7 Of these snakes with limbs, the oldest, Tetrapodophis amplectus, had both forelimbs and hindlimbs (but see the update for 5 December 2006 here). Eupodophis, discovered in 2000, was found in sediments in Lebanon. It had a hind limb, complete with a femur, tibia and fibula (the upper leg and the two lower leg bones). Another species, belonging to the genus Najash had a sacrum8 and robust, functional hindlimbs positioned outside of its ribcage.9 Today some living snake species, such as boas or pythons even have small bones in their pelvic areas. This fossil trend (no limbs, limbs gained, then lost) completely contradicts the evolutionary concept of a gradual loss of limbs from a four-limbed snake ancestor.

Fossils of snakes with legs most likely formed during the Genesis Flood, so they could have arisen after Creation week. A possible creationist explanation is that God cursed the snake right after the Fall in such a way as to turn off certain genetic elements in its genome, which coded for limbs. As to which species of snake this might have been, we don’t know. Sometime later after the Fall, mutations could have switched these genetic elements back on. These elements could have been damaged by further mutations later on.

This may explain why the HA1 gene, mentioned by Emerling, is found in snakes, albeit in an apparently degraded, functionless form. The degraded HA1 gene is inactive, and thus, snakes with this inactive gene variant don’t have legs. The loss of legs most likely happened in both lizards and snakes, affecting the HA1 and HA2 genes, which are present in both animal groups.

Table 2. List of fossil snake species

Species Assumed evolutionary age (mill. of years)11 Morphology Geographical location
Eophis underwoodi 167 limbless Oxfordshire, England
Portugalophis lignites 157–152 limbless Guimarota, Portugal
Diablophis gilmorei 155 limbless Colorado, USA
Parviraptor estesi 145–140 limbless Dorset, England
Tetrapodophis amplectus 113 all four limbs Brazil
Haasiophis terrasanctus 100–94 hindlimbs Ramallah
Xiaophis myanmarensis 99 limbless Myanmar
Pachyrachis problematicus 98–94 hindlimbs Ramallah
Eupodophis descouensi 94 hindlimbs Lebanon
Najash rionegrina 90 sacrum and hindlimbs Rio Negro, Argentina

Is this proof of evolution?

The loss of limbs and wings have been documented in birds and also insects and have been shown to fail as evidence for evolution. Not only that, but loss of both taste buds and vision have occurred in snakes. ‘Limblessness’ is also not a trait that helps evolution because anatomical structures have been lost not gained. This is the exact opposite of what evolution needs to proceed towards creating new body plans. Genes as well as the multiple anatomical structures that they code for have been lost in these animals. Legs, taste buds and elements of the visual system were not observed to re-evolve.

It was rather surprising to read that Emerling did not make the obvious biblical connection when studying the loss of limbs in snakes. Genesis 3:14 says:

“Because you have done this, cursed are you above all livestock and above all beasts of the field; on your belly you shall go, and dust you shall eat all the days of your life.” (emphasis added)

This is the true origin of how at least some snakes came to crawl on their bellies, according to the Bible. Snakes are also known to ‘eat dust’. Therefore, the evidences from genetics as well as from body morphology and the fossils are all in line with the biblical account. Emerling’s article on snakes does not prove evolution, nor does it disprove the Bible, rather the opposite: it supports the historical events in Genesis as true.

Questions for evolutionists

Now that we have answered the questions posed by Emerling, we have some questions of our own for people who may be convinced of his evolutionary arguments:

  1. How does loss of genetic and anatomical structures provide evidence for (microbes-to-man) evolution?
  2. Based on evolutionary reasoning and the fossil record, snakes would have gained legs and then lost them. How do you explain these reversals?
  3. Why do you think snakes evolved from lizards if there are fossil snake species with legs?10 Wouldn’t it make more sense to say that older snake species with legs gave rise to modern legless snakes via loss of genetic elements?
  4. Snakes are very different from lizards. What kind of mutations are responsible for transforming lizards into snakes?

References and notes

  1. Dalla Valle, L. et al, Deleterious mutations of a claw keratin in multiple taxa of reptiles, Journal of Molecular Evolution 72(3):265–273, 2011. Return to text.
  2. Gene degradation wouldn’t necessarily mean that snakes devolved from lizards since such degradation could have occurred independently in both groups. Indeed, there is some evidence that opsin and light-associated genes show degradation in snakes. Return to text.
  3. Emerling, C.A., Genomic regression of claw keratin, taste receptor and light-associated genes provides insights into biology and evolutionary origins of snakes, Molecular Phylogenetics & Evolution 115:40–49, 2017 | doi:10.1016/j.ympev.2017.07.014. Return to text.
  4. Sodera, V., One small speck to man, the evolution myth 2, Bekaam Printers Pte Ltd, Malaysia, 2009. Return to text.
  5. Wood, T.C., Animal and Plant Baramins, Center for Origins Research Issues in Creation, No. 3, Wipf & Stock Publishers, Eugene, OR, 2008. Return to text.
  6. Bell, P., Of snakes, lizards and mosasaurs, Creation 31(3):15–17, 2009; creation.com/snakes. Return to text.
  7. Bell, P., Baby snake fossil further frustrates evolution, Creation 41(3):15, 2019. Return to text.
  8. A triangular-shaped bone formed from the fusion of vertebrae at the end of the spinal column between the two hipbones. Return to text.
  9. Apesteguía, S., & Zaher, H., A Cretaceous terrestrial snake with robust hindlimbs and a sacrum, Nature 440(7087):1037–1040, 2006. Return to text.
  10. Some evolutionists favour an aquatic origin for snakes, see ref. 6. Return to text.
  11. Evolutionary age estimates for some fossil snake species retrieved from fossilworks.org/. Return to text.