11E- The Earth Brought Forth Mammals (optional excursus)

An excursus is similar to an appendix and provides a digression from the main text. The excursuses are completely optional and are not part of the course. The excursuses in first 12 chapters are my updates to a popular interpretation of the first chapter of Genesis in the 19th century: the day-age interpretation of Arnold Guyot. 

The sixth day begins

The first two verses of the sixth day describe two phases of mammals. This chapter focuses on v. 24. The lack of a definite article in v. 24 indicates that the animals of v. 24 were not quite in the form of modern mammals.

Genesis 1:24. Then God said, “Let the earth bring forth living creatures after their kind: cattle and creeping things and beasts of the earth after their (its) kind”; and it was so. 25 God made the beasts of the earth after their kind, and the cattle after their kind, and everything that creeps on the ground after its kind; and God saw that it was good. 

The reason that most theologians think that the animals in the sixth day were mammals is that beasts of the earth was a Hebrew term that generally referred to lions, dogs, and other carnivores, Behemah, translated as cattle, was a Hebrew term that generally referred to large herbivores such as cattle, deer, or sheep. Creeping things refers to small animals, including mammals and lizards. 

Mammals began as reptiles in the Carboniferous (bottom of Figure 11-2). During the Mesozoic, mammal ancestors evolved thermoregulation, birth of live young, mammary glands, and hair. Were these just random events or were they predictable, such that God would know that they would occur? I asked the following question of Bing AI. “Did selection pressure cause the evolution of thermoregulation, birth of live young, mammary glands, and hair in mammals?"

“Yes, selection pressure played a role in the evolution of thermoregulation, birth of live young, mammary glands, and hair in mammals. The evolution of these traits was driven by a number of factors, including the need to adapt to changing environments and the need to protect and nourish offspring. 

Thermoregulation is the ability of an organism to maintain a constant body temperature despite changes in the environment. Mammals are endothermic, which means they generate heat internally and can maintain a constant body temperature even in cold environments. This adaptation allowed mammals to survive in a wide range of environments, from polar regions to deserts. 

Live birth is another adaptation that allowed mammals to survive in changing environments. Unlike reptiles and birds, which lay eggs on land, mammals give birth to live young that are nourished by the mother’s body before and after birth. This adaptation allowed mammals to reproduce in a wider range of environments and provided greater protection for offspring. 

Mammary glands are another adaptation that evolved in mammals. These glands produce milk, which provides nourishment for offspring after birth. This adaptation allowed mammals to provide their young with a reliable source of nutrition, even in harsh or changing environments. 

Finally, hair is another adaptation that evolved in mammals. Hair provides insulation and protection from the environment, as well as sensory information about the environment. This adaptation allowed mammals to survive in a wide range of environments and to exploit new ecological niches.” 

The known selection pressures indicate that God knew that mammals would evolve from reptiles. The parallel evolutionary tracks of mammals and dinosaurs/birds (Figure 3I-1) and the influence of dinosaurs on the lifestyles of mammals indicate that the world of dinosaurs was an important and necessary part of God ‘s plan for the ultimate evolution of mammals and finally humans. In addition to the competition with dinosaurs, the climate changes and extinctions based on the positions of continents and other factors played a major role in the evolution of mammalian characteristics during the Mesozoic.

Reptilian mammal ancestors dominated the single large continent of Pangaea during the Permian (Section 11-2). The sequence in the Permian was pelycosaurs, therapsids, and cynodonts (Figure 11-1 and 11-2). The cynodonts evolved from the therapsids in the late Permian (Figure 11-2). The cynodonts survived the Great Permian Extinction (251 Ma) and evolved in the Triassic (Section 11-3). At that time, the archosaurs (dinosaurs and crocodilians) dominated the world and played a major role in cynodont evolution by forcing them into ecological niches such as hunting at night (Section 11-3). The first true mammals with mammalian characteristics appeared at the end of the Triassic (225 Ma). At this point, they were small and nocturnal to avoid the dinosaurs. This lifestyle was the primary lifestyle of mammals until the end of the dinosaurs in the End Cretaceous extinction. In order to survive in this world, they developed advanced senses of smell and hearing during the Early Jurassic.

One reason to the think that early mammal evolution in the Age of Reptiles was primarily the result of natural processes is that v. 24 states, let the earth bring forth living creatures… livestock, etc…. This is in contrast with v. 25, which states that God formed the beasts of the earth, livestock, etc… Thus, if there was a period of mammal evolution that was more oriented toward natural processes, then it was probably the Mesozoic. Although selection pressures and random mutation were the normal cause of changes in mammals, God is not a philosophical naturalist. God is not opposed to intervening in the earth’s or life’s processes. Thus, God might also have intervened in the process of mammal evolution. For example, God might have caused a change in climate. For example, the Great Permian extinction eliminated the large synapsids and opened up the ecosystem to dinosaurs and birds, and crocodilians, which influenced mammal evolution and caused mammals to become small nocturnal creatures. After the Permian, the giant continent of Pangaea and associated dry climate also influenced mammalian evolution.

Section 11-4 reviews the final phase of mammal evolution in the world of dinosaurs. The first metatherian (marsupial) mammals appeared in the early Cretaceous. The eutherians, which became the placental mammals after the End Cretaceous extinction, appeared in the Late Jurassic, and evolved during the entire period of the Cretaceous (145 – 65 Ma). The Zhalambdalestidae (rodents and primates), Zhelestidae (ungulates), and Cimolestes (carnivores) were eutherian mammals. One important advance in the eutherians is that they developed the hyoid bone, which enabled them to make sounds. The hyoid bone indicates the evolving social skills of these mammals in the Cretaceous. The other indication of socialization among eutherians is that the eutherians evolved the corpus callosum, which allows for communication between the left and right sides of the brain. This is considered an essential part of placental mammal social skills and other aspects of intelligence. While social skills and senses evolved in the Jurassic and Cretaceous, scientists think that much of placental mammal intelligence and continued sensory development took place after the End Cretaceous extinction.

Verse 25 indicates that God influenced mammal evolution (“God made”). One way in which God might have intervened was to destroy the dinosaurs. The Chicxulub asteroid destroyed the dinosaurs at the end of the Cretaceous Period (66 Ma) and opened the ecosystems for mammals. The story of the discovery of this asteroid is one of the more fascinating stories in science (Section 11-5). The End Cretaceous extinction was also caused by an enormous magma event in India, the Deccan Traps, that released sulfur dioxide into the air and acidified the surface layers of the seas (Section 11-6). Scientists had long been puzzled about the End Cretaceous extinction. After the discovery of the Chicxulub asteroid and the Deccan Traps, there was a long debate about which disaster caused the extinction of the dinosaurs (Section 11-7) and the survival of mammals.

Did God play a role in the asteroid impact? The End Cretaceous extinction selectively eliminated dinosaurs and the large marine reptiles, but it did not eliminate ocean fish, ocean shellfish, freshwater fish, other aquatic species, land plants, small land mammals, lizards, or snakes – all the good animals for a healthy mammalian dominated ecosystem.  This event allowed mammals to diversify, live in the day, reach large size, and reach their present form and diversity.

Extinction events are not necessarily due to divine intervention. There were five major extinction events in the Phanerozoic Eon although none were caused by asteroids. Large asteroids circle the solar system and have hit the earth in the past, including two of comparable size with the Chicxulub asteroid These asteroids hit Australia 300 million years ago, but not in a location that caused an environmental catastrophe. In the End Cretaceous extinction, the asteroid hit a volatile oil deposit, which resulted in large emissions of soot and/or sulfur, causing an immediate climate catastrophe. The catastrophe killed all plant life for 10 years, such that the only terrestrial animals that survived were insects or other animals that consumed plant detritus and those animals that consumed insects. The magma event created acidic surface conditions in the ocean, which was deadly for marine reptiles. The elimination of dinosaurs and marine reptiles, and not small reptiles, birds, mammals, and fish should be considered finely tuned.  

Kaino determined that 87% of the earth has lower hydrocarbon density than the Chicxulub impact site.[1] If the Chicxulub asteroid had struck a location with lower hydrocarbon density, then it would not cause a similar level of extinction. Another consideration is the angle of impact. The asteroid hit at a 45-to-60-degree angle. Only 1/4 of asteroids hit the Earth at an angle that is 60 degrees or greater. Asteroids that come at a steep angle are much deadlier.[2] 

"A study in 2020 showed that the asteroid came from the northeast at a steep angle. This maximized the amount of climate-changing gas that was launched into the atmosphere and was one of the deadliest possible scenarios. The study says that their 3d simulations showed that the impactor hit at a 40- to 60-degree angle. " Credit: Wikipedia, Chicxulub impactor 

Bottke et al.[3] proposed that the Chicxulub asteroid came from the Baptistina asteroid family. Geologic evidence indicates that the Chicxulub asteroid was probably a carbonaceous chondrite, which is the type of asteroid in the Baptistina family.[4] Bottke worked backward from current asteroid paths and determined that a disturbance might have taken place 160 million years ago that caused this family of asteroids. This would have allowed for the Chicxulub asteroid to reach Earth 65 million years ago; however, more recent research indicates that the disturbance that caused the Baptistina family took place 80 million years ago,[5] which might indicate that the path was not naturally induced.

The other contributor to the extinction event was the flood basalt event that formed the Deccan Traps. As with asteroids, flood basalt events also occur periodically; however, the End Cretaceous extinction was the only joint occurrence of a flood basalt event and a giant asteroid impact in the Phanerozoic Eon. This dual cause might have facilitated the fine tuning of the extinction event, both from the perspective of an impact on land and sea, and with catastrophic events on opposite sides of the world. In addition, the asteroid caused a massive earthquake that probably exacerbated the release of basalt, both in India and around the world.

Although it is impossible to know whether the Chicxulub asteroid and flood basalt event were natural processes without any divine intervention, it had a specific effect at a specific time that caused the extinction of dinosaurs and the evolution of mammals. Does it really matter, from a philosophical perspective, whether God diverted the asteroid at a specific time in the Mesozoic or whether God knew that the asteroid would impact a highly volatile location in 66 Ma, at the same time as a similarly lethal flood basalt event. The effect was the same, the extinction of the dinosaurs and the opening of ecosystems for mammals. Whether or not there was a specific divine intervention, the impact enabled the evolution of mammals and eventually humans.

Another candidate for the divine intervention is the second biggest problem in paleontology. There were three branches of nonplacental mammals prior to the End Cretaceous extinction and three branches of placental mammals descended from them after the End Cretaceous extinction. There was an explosive radiation of placental mammals after the End Cretaceous extinction (Section 4-8). This event has caused great controversy among paleontologists. Why did three branches suddenly become placental at the same time? Section 5-1 discusses whether this was also due to divine intervention.

The following episode of Days (Eons) of our lives helps gain perspective on the danger for mammals living in the Age of Reptiles

Days (Eons) of Our Lives             Episode 4

Mamie the Cretaceous Protomammal
Bob the Prehistoric Carnivorous Bird

Mamie: You guys are really scary.

Bob: Jaws, wings, and talons are all within the vertebrate body plan so it must be God's will. Its all part of the plan.

Mamie: I'm actually okay with it. I can go out at night and hunt bugs when you guys are sleeping.
Bob: You are pretty smart.

Mamie: You have to be smart to live in this dangerous world. What I like to say is that if you can live here, then you can live anywhere. You guys are really amazing. I love the colored feathers.

Bob: You guys are amazing also. I love the fur.

Mamie: Right, between the fur and the thermoregulation, we stay pretty warm.

Bob: I am kind of hoping that we can hang out together for a few hundred million years.

Mamie: You don't really have a very good reputation, Bob, as a friend of mammals.

Bob: Mamie, I heard you were a flirtatious protomammal

Mamie: Far from it. I am a Cretaceous protomammal. I don't hang out with prehistoric carnivorous birds. I would rather stay alive; however, I would like to acknowledge that staying away from you helps me to become a better mammal, evolving better hearing with which to hear you coming, and better sight and smell to see and smell you, as well as insects.

Morton and Guyot debate the meaning of the sixth day. 

Guyot thought that vss. 24-25 described mammals and that this was the Age of Mammals and then mankind. At the time, scientists knew that there was a sharp break between the Age of Reptiles and the Age of Mammals; thus, Guyot argued that the three types of animals in vv. 24-25 were mammals. Guyot thought that "The creeping animals of the sixth day are not reptiles," and referred to Gesenius to justify the interpretation that they were "the smaller mammalia-rats, mice, etc."[6] Morton's article, Morton presented the complete Gesenius reference in order to contradict Guyot's assertion that Moses' sixth day referred to mammals because creeping things could also refer to lizards.[7] Morton then offered the following assessment of Guyot. 

"Admitting as I do freely the learning and piety of Professor Guyot, I must confess myself as entirely unable to account for this assertion as to the statement of Gesenius, but must leave it, with several other passages in his book, as among the inexplicable mental operations of one advocating a favorite theory which encounters radical obstructions." 

Morton was correct that creeping things could refer to lizards, but the context probably indicates that small mammals was the meaning of creeping things in vv. 24 and 25. The other animals in these verses were the large land mammals. Thus, the aspect of creeping things that is probably referred to in these verses were the mammal creeping things.

Guyot also mentioned that humans were last in the order of the fossil record and in the order of the six days, but Morton did not comment on this assertion, probably because it was obvious at the time. 

In retrospect, Morton's consistent level of condescension and ridicule toward a member of the National Academy of Sciences in a peer-reviewed publication (Bibliotheca Sacra) is interesting. I am not sure why he felt the need to behave in this way or why the reviewers allowed it. Possibly, it was normal at the time. In retrospect, however, Morton's incorrect claims of animals before plants, no birds in the Mesozoic, and the lack of focus on mammals in the Moses' sixth day, accompanied by his ridicule and condescension, are somewhat regrettable. The sad thing is that Guyot's interpretation of the cosmogony of the universe and solar system in the first four days and the order of life in the fifth and sixth days was rejected due to an immature development of natural history in the 19th century.

References

[1] Kaiho, Kunio, and Naga Oshima. "Site of asteroid impact changed the history of life on Earth: the low probability of mass extinction." Scientific reports 7, no. 1 (2017): 1-12.

[2] Collins, Gareth S., N. Patel, Thomas M. Davison, A. S. P. Rae, Joanna V. Morgan, and Sean PS Gulick. "A steeply-inclined trajectory for the Chicxulub impact." Nature communications 11, no. 1 (2020): 1-10.

[3] Bottke, William F.; Vokrouhlický, David; Nesvorný, David (2007). "An asteroid breakup 160 Myr ago as the probable source of the K/T impactor". Nature. 449 (7158): 48–53. doi:10.1038/nature06070. ISSN 0028-0836.

[4] Wikipedia article, Chicxulub impactor.

[5] Tammy Plotner, Did Asteroid Baptistina Kill the Dinosaurs? Think other WISE... in Universe Today (2011) at universetoday.co

[6] Guyot, Arnold. Creation: Or, the biblical cosmogony in the light of modern science. C. Scribner’s Sons; 1884.

[7] Morton, President Henry. "The cosmogony of Genesis and its reconcilers." Bibl. Sacra 54 (1897): 27.

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Asteroid impact: NASA