Argument from poor design

Artist's representation of an ectopic pregnancy. Critics cite such common biological occurrences as contradictory to the 'watchmaker analogy'.

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.[7]
• 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. A result is that, 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."[8]

• Barely used nerves and muscles, such as the plantaris muscle of the foot,[9] 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.[10]
• 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.[11]
• Almost all animals and plants synthesize their own vitamin C, but humans cannot because the gene for this enzyme is defective (Pseudogene ΨGULO).[12] 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.[13]
• The prevalence of congenital diseases and genetic disorders such as Huntington's disease.
• 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.[14]
• 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.[15] 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.[16] However, an 'inverted' retina actually improves image quality through müller cells by reducing distortion.[17] 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.[18]
• 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.

• In the African locust, nerve cells start in the abdomen but connect to the wing. This leads to unnecessary use of materials.[7]
• Intricate reproductive devices in orchids, apparently constructed from components commonly having different functions in other flowers.
• The use by pandas of their enlarged radial sesamoid bones in a manner similar to how other creatures use thumbs.[7]
• The existence of unnecessary wings in flightless birds, e.g. ostriches.[19]
• 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.
• The loss of tetrachromatic vision by mammals as compared to other tetrapods.
• The enzyme RuBisCO has been described as a "notoriously inefficient" enzyme,[20] 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.[21]
• 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 says the ancestor 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.

Several generic philosophical criticisms can be directed towards the first premise of the argument – that a Creator deity would have designed things 'optimally'. The argument hinges on an assumption that the human concept of 'optimal design' is the same as that of a theistic god. This is, in effect, the argument for the incomprehensibility of the Abrahamic God Yahweh in the Book of Job:

Then the LORD answered Job out of the whirlwind, and said, Who is this that darkeneth counsel by words without knowledge? Gird up now thy loins like a man; for I will demand of thee, and answer thou me. Where wast thou when I laid the foundations of the earth? Declare, if thou hast understanding. Who hath laid the measures thereof, if thou knowest? Or who hath stretched the line upon it? Whereupon are the foundations thereof fastened? Or who laid the corner stone thereof, when the morning stars sang together, and all the sons of God shouted for joy?[22]

The Book of Job goes on to list a number of aspects of the world that seem wonderful or miraculous beyond human understanding. The claim is that, if humans have no understanding of how the wonders of the world were created, they cannot fully understand the things that appear flawed.

Others argue that the observed suboptimality in one system or another is intentional, as a trade-off to improve overall optimal design.[23]

Intelligent design proponent William Dembski questions the first premise of the argument, claiming that "intelligent design" does not need to be optimal.[24] An article written by John Woodmorappe on the Creation Ministries International website says that the panda's "thumb" works well for what the panda uses it for – to strip leaves.[25]

While the appendix has been previously credited with very little function, research has shown that it serves an important role in the fetus and young adults. Endocrine cells appear in the appendix of the human fetus at around the 11th week of development, which produce various biogenic amines and peptide hormones, compounds that assist with various biological control (homeostatic) mechanisms. In young adults, the appendix has some immune functions.[26]

Creationist Jonathan Sarfati and ophthalmologist Peter Gurney have both published articles on the Creation Ministries International website which disagree that the human eye is poorly designed, arguing that alternative arrangements would have further complications and that the human eye actually works very well.[27][28]