question: Why are human babies so helpless compared to other babies in the animal kingdom?
comment: It's evolutionary advantageous. Babies take a lot of calories to grow. When they are still inside of the mother, the goal is to get the baby out as soon as possible. This requires a lot of calories and creates a lot of strain on the mother. Once born, the baby's systems are mostly self-sufficient, the toll on the mother is less, and the growth of the baby can slow. However, a consequence of this fast-slow development is that the baby is pretty helpless. This would be a problem for a lot of animals, as they do not have the ability to nurture or carry their young. Animals that are in danger of being prey are especially susceptible. Humans, and other mammals with the ability to care and carry their young to relative safety, tend to birth "under-developed" offspring. Also, as a baby's brain develops, it requires stimulation. The earlier the stimulation can start, the more information the baby can learn. livescience wrote a brief summary about it which can be found [here]( URL_0 ).
passages: Physiological prematurity
  
  The term physiological prematurity refers to the fact that compared to most animals, humans are born in a premature biological state. Although sensory organs and skeletal and muscular systems are largely developed prenatally, human babies at the time of their birth are completely helpless and dependent on intensive care. This is in contrast to the maturity at birth found in other higher mammals (e.g. elephants, horses). 
   Human infants are also almost always born with assistance from other humans because of the way that the pelvis is shaped. Since the pelvis and opening of birth canal face backwards, humans have difficulty giving birth themselves because they cannot guide the baby out of the canal. Non-human primates seek seclusion when giving birth because they do not need any help due to the pelvis and opening being more forward. Human infants depend on their parents much more and for much longer than other primates. Humans spend a lot of their time caring for their children as they develop whereas other species stand on their own from when they are born. The faster an infant develops, the higher the reproductive output of a female can be. So in humans, the cost of slow development of their infants is that humans reproduce relatively slowly. This phenomenon is also known as cooperative breeding.
   As a consequence of bipedalism, human females have narrower birth canals. The construction of the human pelvis differs from other primates, as do the toes. A trade-off for these advantages of the modern human pelvis is that childbirth is more difficult and dangerous than in most mammals, especially given the larger head size of human babies compared to other primates. Human babies must turn around as they pass through the birth canal while other primates do not do, which makes humans the only species where females usually require help from their conspecifics (other members of their own species) to reduce the risks of birthing. As a partial evolutionary solution, human fetuses are born less developed and more vulnerable. Chimpanzee babies are cognitively more developed than human babies until the age of six months, when the rapid development of human brains surpasses chimpanzees. Another difference between women and chimpanzee females is that women go through the menopause and become unfertile decades before the end of their lives. All species of non-human apes are capable of giving birth until death. Menopause probably developed as it provides an evolutionary advantage of more caring time to relatives' young.
   Development at birth varies considerably among animals, and even among mammals. Altricial species are relatively helpless at birth and require considerable parental care and protection. In contrast, precocial animals are born with open eyes, have hair or down, have large brains, and are immediately mobile and somewhat able to flee from, or defend themselves against, predators. Primates are precocial at birth, with the exception of humans.
  
  The duration of gestation in placental mammals varies from 18 days in jumping mice to 23 months in elephants. Generally speaking, fetuses of larger land mammals require longer gestation periods.
   The gestation period is eight months. Care for the young is provided mostly by their mothers. The survival and emotional health of the young is dependent on maternal care. Mothers provide their young with food, warmth, and protection, and teach them certain skills. In addition, a chimp's future rank may be dependent on its mother's status. Newborn chimps are helpless; their grasping reflex is not strong enough to support them for more than a few seconds. For their first 30 days, infants cling to their mother's bellies. Infants are unable to support their own weight for their first two months and need their mothers' support.
   Early human ancestors, hominids, originally gave birth in a similar way that non-human primates do because early obligate quadrupedal individuals would have retained similar skeletal structure to great apes. Most non-human primates today have neonatal heads that are close in size to the mother's birth canal, as evidenced by observing female primates who do not need assistance in birthing, often seeking seclusion away from others of their species. In modern humans, parturition (childbirth) differs greatly from the rest of the primates because of both pelvic shape of the mother and neonatal shape of the infant. Further adaptations evolved to cope with bipedalism and larger craniums were also important such as neonatal rotation of the infant, shorter gestation length, assistance with birth, and a malleable neonatal head.
   Obstructed labor is unique to humans compared to other primates. The evolution of humans to become obligate bipedal and increase in brain size create the problems associated with obstructed labor. In order for bipedal locomotion to be possible, many changes had to occur to the skeletal structure of humans, especially in the pelvis. Both the shape and orientation of the pelvis changed. Other primates have straighter and wider pelvises compared to humans. A narrow pelvis is better for bipedal locomotion but makes childbirth more difficult. The pelvis is sexually dimorphic, with females having a wider pelvis to be better suited for childbirth. However, the female pelvis still must accommodate for bipedal locomotion which is what creates the challenges for obstructed labor. The brain size of humans has also increased as the species has evolved, resulting in a larger head of the fetus that must exit the womb. This requires human infants to be born less developed when compared to other species. The bones of the skull are not yet fused when a human infant is born in order to prevent the head from becoming too large to exit the womb. However, the head of the fetus is still large and poses the possibility for obstructed labor.
   The solution to this was to give birth at an early stage of fetal development, before the skull grew too large to pass through the birth canal. This adaptation enabled the human brain to continue to grow, but it imposed a new discipline. The need to care for helpless infants for long periods of time forced humans to become less mobile. Human bands increasingly stayed in one place for long periods, so that females could care for infants, while males hunted food and fought with other bands that competed for food sources. As a result, humans became even more dependent on tool-making to compete with other animals and other humans, and relied less on body size and strength.
   The fetuses of most mammals are situated similarly to the human fetus within their mothers. However, the anatomy of the area surrounding a fetus is different in litter-bearing animals compared to humans: each fetus of a litter-bearing animal is surrounded by placental tissue and is lodged along one of two long uteri instead of the single uterus found in a human female.
   Gestation length in humans is believed to be shorter than most other primates of comparable size. The gestation length for humans is 266 days, or eight days short of nine months, which is counted from the first day of the woman's last menstrual period. During gestation, mothers must support the metabolic cost of tissue growth, both of the fetus and the mother, as well as the ever-increasing metabolic rate of the growing fetus. Comparative data from across mammals and primates suggest that there is a metabolic constraint on how large and energetically expensive a fetus can grow before it must leave the mother's body. It is thought that this shorter gestation period is an adaptation to ensure the survival of mother and child because it leads to altriciality. Neonatal brain and body size have increased in the hominin lineage, and human maternal investment is greater than expected for a primate of our body mass. The obstetrical dilemma hypothesis suggests that in order to successfully undergo childbirth, the infant must be born earlier and earlier, thereby making the child increasingly developmentally premature. The concept of the infant being born underdeveloped is called altriciality. Humans are born with an underdeveloped brain; only 25% of their brains fully developed at birth as opposed to non-human primates where the infant is born with 45–50% brain development. Scientists have believed that the shorter gestation period can be attributed to the narrower pelvis, as the baby must be born before its head reaches a volume that cannot be accommodated by the obstetric canal.
   Section::::Mammals.:Primates.
  
  Primates are born with intermediate maturation of altricial and precocial species. Newborns have limited motor functioning, but have highly developed sensory systems and the ability to thermoregulate. A unique characteristic in the maternal behavior in primates is that the mothers carry their young until their locomotive abilities develop. The mother will either carry the young in their arms, or the young will attach itself to the mother and cling to her. This is known as matricolia.
  
  Section::::Birds.
  
  "Main article:" Parental care in birds
   The conflict between the size of the human foetal brain at birth, (which cannot be larger than about 400 cm, else it will not get through the mother's pelvis) and the size needed for an adult brain (about 1400 cm), means the brain of a newborn child is quite immature. The most vital things in human life (locomotion, speech) just have to wait while the brain grows and matures. That is the result of the birth compromise. Much of the problem comes from our upright bipedal stance, without which our pelvis could be shaped more suitably for birth. Neanderthals had a similar problem.
   At the opposite end of the spectrum are precocial animals in which the young have open eyes, have hair or down, have large brains, and are immediately mobile and somewhat able to flee from, or defend themselves against, predators. For example, with ground-nesting birds such as ducks or turkeys, the young are ready to leave the nest in one or two days. Among mammals, most ungulates are precocial, being able to walk almost immediately after birth. Beyond the precocial are the superprecocial animals, such as the megapode birds, which hatch with full flight feathers.
  
  Section::::Basis.
   Primates have slower rates of development than other mammals. All primate infants are breastfed by their mothers (with the exception of some human cultures and various zoo raised primates which are fed formula) and rely on them for grooming and transportation. In some species, infants are protected and transported by males in the group, particularly males who may be their fathers. Other relatives of the infant, such as siblings and aunts, may participate in its care as well. Most primate mothers cease ovulation while breastfeeding an infant; once the infant is weaned the mother can reproduce again. This often leads to weaning conflict with infants who attempt to continue breastfeeding.
   In humans and some other primates, the head of the term fetus is so large in comparison to the size of the birth canal that delivery may result in some degree of trauma.
  
  As the head passes through the pelvis, the soft tissues are stretched and compressed. The risk of severe tear is greatly increased if the fetal head is oriented occiput posterior (face forward), if the mother has not given birth before or if the fetus is large.
   Infant mortality in the wild is at its highest during weeks 5–15 of their lives, when they begin to move around and explore on their own, this is because one of the greatest threats to infant survival is falling from the canopy.
  
  Section::::Distribution.
   The obstetrical dilemma also makes birth more difficult and results in increased maternal investment. Humans have evolved both bipedalism and large brain size. The evolution of bipedalism altered the shape of the pelvis, and shrunk the birth canal at the same time brains were evolving to be larger. The decreasing birth canal size meant that babies are born earlier in development, when they have smaller brains. Humans give birth to babies with brains 25% developed, while other primates give birth to offspring with brains 45-50% developed. A second possible explanation for the early birth in humans is the energy required to grow and sustain a larger brain. Supporting a larger brain gestationally requires energy the mother may be unable to invest.
   The ethics of pulling a baby primate away from their mother at young ages isn't morally right. Removing baby primates from their mothers can cause high psychological trauma in these young primates that can inhibit proper growth and social skills. In addition to lasting effects, these animals may live in small, cramped, dirty environments, which can cause health issues within baby primates. Health problems can also arise sooner and with more impact on a young primate that has just been removed from the comfort of their mother because their immune system is not fully active as it would be with an older primate. The psychological effects of the physiological suffering of these young primates last a lifetime.
   Females den in hollow trees. Kits are born blind and helpless. They are partially covered with fine hair. Kits begin to crawl after about three weeks. After about seven weeks, they open their eyes. They start to climb after eight weeks. Kits are completely dependent on their mother's milk for the first eight to ten weeks, after which they begin to switch to a solid diet. After four months, kits become intolerant of their litter mates, and at five months, the mother pushes them out on their own. After one year, juveniles will have established their own range.
   When such premature babies are born, the main causes of mortality are that the respiratory system and the central nervous system are not completely differentiated. If given expert postnatal care, some preterm babies weighing less than may survive, and are referred to as "extremely low birth weight" or "immature infants".
  
  Preterm birth is the most common cause of infant mortality, causing almost 30 percent of neonatal deaths. At an occurrence rate of 5% to 18% of all deliveries, it is also more common than postmature birth, which occurs in 3% to 12% of pregnancies.
  
  Section::::Circulatory system.
  
  Section::::Circulatory system.:Before birth.
   The shortening of the pelvis and smaller birth canal evolved as a requirement for bipedalism and had significant effects on the process of human birth which is much more difficult in modern humans than in other primates. During human birth, because of the variation in size of the pelvic region, the fetal head must be in a transverse position (compared to the mother) during entry into the birth canal and rotate about 90 degrees upon exit. The smaller birth canal became a limiting factor to brain size increases in early humans and prompted a shorter gestation period leading to the relative immaturity of human offspring, who are unable to walk much before 12 months and have greater neoteny, compared to other primates, who are mobile at a much earlier age. The increased brain growth after birth and the increased dependency of children on mothers had a big effect upon the female reproductive cycle, and the more frequent appearance of alloparenting in humans when compared with other hominids. Delayed human sexual maturity also led to the evolution of menopause with one explanation providing that elderly women could better pass on their genes by taking care of their daughter's offspring, as compared to having more children of their own.
   During the hominin’s early evolution, brains became larger, due to increased intelligence, and bipedalism became the norm. The consequences of these two changes in particular resulted in painful and difficult labor due to the increased favor of a narrow pelvis for bipedalism being countered by larger heads passing through the constricted birth canal. This phenomenon is commonly known as the obstetrical dilemma.
  
  Section::::Physiology.
  
  Bipedal movement occurs in a number of ways, and requires many mechanical and neurological adaptations. Some of these are described below.
  
  Section::::Physiology.:Biomechanics.
  
  Section::::Physiology.:Biomechanics.:Standing.
   Section::::Mammals.:Marsupials.
   There is no monogamy, and males play no part in the raising of young. Hatchlings are born with an egg tooth, and are essentially miniature versions of the adults. They do not vocalise as frequently as human children unless urged to do so, a defence mechanism against predators. Unlike human babies who crave physical contact, Race hatchlings instinctively avoid anything larger than themselves. At the age of 3 months, Race hatchlings become predatory in nature and have to be taught not to attack their own kind. Due to their considerably greater physiological development and self-reliance at birth, cases of surviving feral children are much more common in the history of The Race than in that of humans.
   Complications for the infant include limitations in body growth since the number and size of cells in tissues is smaller. The infant likely did not receive enough oxygen during pregnancy so the oxygen level is low. It is also more difficult to maintain body temperature since there is less blood flow within the small body.
  