Do kangaroos have nightmares? Maybe. Little children sure do.
“Daddy…” A small voice called me punctuated by little sobs.
I had just put on my pajamas after showering. Hopefully he hadn’t been calling for very long. I hurried across the hall to Byron’s room and opened the door.
“What’s the matter, little one?” I asked as I sat on the side of his bed.
“I’m scared,” he answered.
“Of what?” I asked.
“A bear.”
“There are no bears in here,” I assured him.
“But one could climb in the window.” He blinked from the light in the hallway. I adjusted my shadow to shield his eyes from the doorway.
“No it can’t,” I told him.
“Why not?”
“Because your window is too high. He would need a ladder to get up here.”
Eventually my logic convinced him he was safe from ladder climbing bears and he went back to sleep. I could have lied to him and given him a magic spray bottle or some such nonsense. But Kim and I always tell our kids the truth. It’s an important value of ours. And his worry about bears was not totally imaginary. Bears did frequent our neighborhood occasionally and his school had recently had to cancel recess due to a bear in the area.
We humans have a complicated relationship with darkness. On one hand, we use massive amounts of electricity to banish the night. Our ancestors stayed close to the fire and reveled in full moons. On the other hand, we relish the anonymity of the night and embrace the cosmos it reveals. We love the warmth of happy ending stories, but take equal pleasure in the chills produced by tales of horror. Our mythology and religions contrast the dark and the light in every origin story.
Halloween is a yearly reminder of our contradictory feelings about light and darkness. It turns out that our fascination and fear of darkness might be genetic. It might also be related to sunburns. These obscure relationships are one reason why I love science so much. It’s complicated so bear with me while I try to explain.
Placental mammals, including humans, lack photo reactivation DNA. This system uses sunlight to repair the damage caused by sunlight (such as sunburns). All other life has this built-in DNA repair kit. We lost this ability due to what scientists refer to as the “nocturnal bottleneck.” This concept refers to how the distant ancestors of all mammals lived and evolved in darkness to avoid dinosaurs. Life in darkness causes certain adaptations in animals, including losing the ability to repair damage done by sunlight. If you never come out in the daytime, then who needs to worry about sun damage?
In the last century, scientists have piled up millions of pieces of evidence about the evolution of life. Exhibit A is all of the characteristics that all mammals share, such as the “nocturnal bottleneck.” One of the first hints that scientists noticed were the common traits found in all mammalian eyes. All of our eyes have adaptations for living in darkness.
Our tiny Mesozoic ancestors loved the safety of the night and it became part of all mammalian DNA. Additional support for this aspect of evolution was recently been discovered in the caves of Somalia. A blind cavefish called Phreatichthys andruzzii was found that is also losing its ability for DNA repair. It has been adapting to life in darkness for about three million years.
Finding different species that have the same gene structure modifications to deal with the same environmental factors reinforces the idea that all living things have a common ancestor. Creationists always fail to “prove evolution wrong” because they can’t produce this crucial piece of evidence. They can’t show a single living thing that doesn’t use guanine, thymine, cytosine, or adenine (the chemical components of DNA) to control their life processes. Even worse for their cause is that different species can use the same gene sequences for the same environmental problems. Or not. Sometimes a different gene sequence can produce the same result.
After the extinction of most dinosaurs, some our ancestors came back into the daylight. Others stayed nocturnal and preyed upon their diurnal cousins. “Lions and tigers and bears, oh my!” Thus our fear of the night and what it can hold developed even as we held onto (at a molecular level) a pull toward the dark.
To be fully human is to be aware of all of the contradictions that come with our evolutionary history. We love the dark. . . we fear the dark. Kangaroos, being marsupials, are not missing the DNA repair kit. So they probably don’t have DNA induced nightmares. An answer to a question you never had.
