In humans Fatal flaws representation of an
ectopic pregnancy. Critics cite such common biological occurrences as contradictory to the '
watchmaker analogy'. American scientist
Nathan H. Lents published his book on poor design in the human body and genome in 2018 titled
Human Errors. The book ignited a firestorm of criticism from the creationist community but was well received by the scientific community and received unanimously favorable reviews in the dozens of non-creationist media outlets that covered it. Several defects in human anatomy can result in death, especially without modern medical care: • In the human female, a
fertilized egg can implant into the
fallopian tube,
cervix or
ovary rather than the
uterus causing an
ectopic pregnancy. The existence of a cavity between the ovary and the fallopian tube could indicate a flawed design in the female reproductive system. Prior to modern surgery, ectopic pregnancy invariably caused the deaths of both mother and baby. Even in modern times, in almost all cases the pregnancy must be aborted to save the life of the mother. • In the human female, the
birth canal passes through the
pelvis. The prenatal skull will deform to a surprising extent. However, if the baby's head is significantly larger than the pelvic opening, the baby cannot be born naturally. Prior to the development of modern surgery (
caesarean section), such a complication would lead to the death of the mother, the baby, or both. Other birthing complications such as
breech birth are worsened by this position of the birth canal. • In the human male,
testes develop initially within the
abdomen. Later during gestation, they migrate through the abdominal wall into the
scrotum. This causes two weak points in the abdominal wall where
hernias can later form. Prior to modern surgical techniques, complications from hernias, such as intestinal blockage and
gangrene, usually resulted in death. • The existence of the
pharynx, a passage used for both
ingestion and
respiration, with the consequent drastic increase in the risk of
choking. • The breathing reflex is stimulated not directly by the absence of
oxygen but indirectly by the presence of
carbon dioxide. This means that high concentrations of inert gases, such as
nitrogen and
helium, can cause suffocation without any biological warning. Furthermore, at high altitudes, oxygen deprivation can occur in unadapted individuals who do not consciously increase their breathing rate. • The human
appendix is a
vestigial organ thought to serve no purpose.
Appendicitis, an infection of this organ, is a certain death without medical intervention. "During the past few years, however, several studies have suggested its immunological importance for the development and preservation of the intestinal immune system." •
Tinnitus, a phantom auditory sensation, is a maladaptation resulting from hearing loss most often caused by exposure to loud noise. Tinnitus serves no practical purpose, reduces quality of life, may cause depression, and when severe can lead to suicide.
Other flaws • Barely used nerves and muscles, such as the
plantaris muscle of the foot, that are missing in part of the human population and are routinely harvested as spare parts if needed during operations. Another example is the muscles that move the ears, which some people can learn to control to a degree, but serve no purpose in any case. • The common malformation of the human spinal column, leading to
scoliosis,
sciatica and congenital misalignment of the vertebrae. The
spinal cord cannot ever properly heal if it is damaged, because neurons have become so specialized that they are no longer able to regrow once they reach their mature state. The spinal cord, if broken, will never repair itself and will result in permanent
paralysis. • The route of the
recurrent laryngeal nerve is such that it travels from the brain to the larynx by looping around the
aortic arch. This same configuration holds true for many animals; in the case of the
giraffe, this results in about twenty feet of extra nerve. • Almost all animals and plants synthesize their own
vitamin C, but humans cannot because the gene for this enzyme is defective (
Pseudogene ΨGULO). Lack of vitamin C results in
scurvy and eventually death. The gene is also non-functional in other
primates and in
guinea pigs, but is functional in most other animals. • The prevalence of
congenital diseases and genetic disorders such as
Huntington's disease. • The male
urethra passes directly through the
prostate, which can produce urinary difficulties if the prostate becomes swollen. • Crowded
teeth and poor
sinus drainage, as human faces are significantly flatter than those of other
primates although humans share the same tooth set. This results in a number of problems, most notably with
wisdom teeth, which can damage neighboring teeth or cause serious infections of the mouth. • The structure of
human eyes (as well as those of all vertebrates). The
retina is 'inside out'. The nerves and blood vessels lie on the
surface of the retina instead of behind it as is the case in many
invertebrate species. This arrangement forces a number of complex adaptations and gives mammals a
blind spot. Having the optic nerve connected to the side of the retina that does not receive the light, as is the case in
cephalopods, would avoid these problems.
Lents and colleagues have proposed that the
tapetum lucidum, the reflective surface behind vertebrate retinas, has evolved to overcome the limitations of the inverted retina, as cephalopods have never evolved this structure. However, an 'inverted' retina actually improves image quality through
müller cells by reducing distortion. The effects of the blind spots resulting from the inverted retina are cancelled by
binocular vision, as the blind spots in both eyes are oppositely angled. Additionally, as
cephalopod eyes lack cone cells and might be able to judge color by bringing specific wavelengths to a focus on the retina, an inverted retina might interfere with this mechanism. • Humans are attracted to
junk food's non-nutritious ingredients, and even wholly non-nutritious
psychoactive drugs, and can experience
physiological adaptations to prefer them to nutrients.
Other life • In the
African
locust,
nerve cells start in the abdomen but connect to the wing. This leads to unnecessary use of materials. • The enzyme
RuBisCO has been described as a "notoriously inefficient" enzyme, as it is
inhibited by oxygen, has a very slow turnover and is not saturated at current levels of carbon dioxide in the atmosphere. The enzyme is inhibited as it is unable to distinguish between carbon dioxide and molecular oxygen, with oxygen acting as a
competitive enzyme inhibitor. However, RuBisCO remains the key enzyme in
carbon fixation, and plants overcome its poor activity by having massive amounts of it inside their cells, making it the most abundant protein on Earth. • Sturdy but heavy bones, suited for non-flight, occurring in animals like bats. Or, on the converse: unstable, light, hollow bones, suited for flight, occurring in birds like penguins and ostriches, which cannot fly. • Various
vestigial body parts, like the femur and pelvis in whales (evolution indicates the ancestors of whales lived on land). •
Turritopsis dohrnii and species of the genus
Hydra have
biological immortality, but most animals do not. • Many species have strong instincts to behave in response to a certain stimulus. Natural selection can leave animals behaving in detrimental ways when they encounter a
supernormal stimulus - like a
moth flying into a flame. • Plants are green and not black, as
chlorophyll absorbs green light poorly, even though black plants would absorb more light energy. •
Whales and
dolphins breathe air, but live in the water, meaning they must swim to the surface frequently to breathe. •
Albatrosses cannot take off or land properly. ==Counterarguments==