Humans are species with internal development. Relate your answer from the Campbell, chapter 47 and consider the species with external development. Would these individuals have a disadvantage because they cannot have their mother to experience these sensations? If it was considered as a disadvantage, would it have any effects on evolution? Or would it be an advantage to not experience the mother's sensation because they can experience various things during development themselves instead of through their mother? How would this have an impact on evolution? What about animals like kangaroos? They are born early, but they need the mother's care such as the pouch. Would it make any difference from different types of development?
Sally Park (sypark1029@gmail.com)
As a rule of thumb, organisms are more complex require more parental care, and so are more likely to have internal development and fertilization. This is highly evident considering that mammals, one of the most highly complex and intelligent groups of organisms, all have internal development and fertilization, as well as a high degree of parental care.
ReplyDeleteHumans require more care than even most other mammals, and this is also due to their complex nature and intelligence. Humans require more than just a few basic instincts to survive – they spend much of their early life, as well as in the womb, developing these mental capabilities. This being true, music being heard in the womb may well have an effect on that baby’s future.
However, this does not necessarily lend a disadvantage to organisms that do not have internal development, as generally the externally developing organisms are much less complex and would not have anything to do with behaviors such as music.
Human babies receive much more than just music in the womb – their internal development means that much of their future genetic expression is affected by everything the mother does.
Mammals, unlike other vertebrates, develop completely internally (Campbell 1033). Because of this, the environment of the mother’s womb can work together with the fetus’s own genetics.
This environmental and genetic interaction is another example of Shenk’s GxE thesis. This extremely close bond between mother and child during early development can greatly aid the child’s development, but sometimes it can be a double edged sword. For example, thalidomide was a drug meant to aid women during pregnancy, but it had the unintended side effect of causing many birth defects (http://www.nytimes.com/2010/03/16/science/16limb.html?pagewanted=all). In this way, externally developing organisms would be at an advantage, as they are not at risk from actions by the mother.
All in all, though, internal development has been the key in the development of complex, intelligent organisms capable of thinking and being creative, such as making music.
David Whisler (dwhis428@gmail.com)
Like the prompt brought up, humans are species with internal development, and after the implantation of the blastocyst in the endometrium of the uterus, the pregnancy will progress into three trimesters (Campbell 1013). During pregnancy, the embryo experiences some of the same external stimuli as the mother, for example, sounds. The ear of the embryo is functional as early as the 16th week of pregnancy, and the fetus listens by the 24th week (Shenk 286). As the embryo listens to the external sounds that its mother listens to, various responses can follow such as heart beat acceleration (in response to loud noises) or distressed movements (such as kicking) (Shenk 286). However, when listening to relaxing sounds such as the mother’s voice or classical music, the baby can even be soothed, or, more strongly, the sounds can help the development of the neural bridges along which thoughts and information travel (http://news.bbc.co.uk/2/hi/455 8507.stm). Also, listening to music “prepares the ear, body and brain to listen to, integrate and produce language sounds” (Shenk 285).
ReplyDeleteConsidering the above fact, I agree with David’s conclusion completely and do not think the species with external development are at much of a disadvantage for not experiencing the same sounds that their mothers experience. This is because the species with external development, such as frogs, do not have as strong a need for linguistic development as humans do. In fact, frogs undoubtedly make sounds, but these are typically innate. Therefore, there is no evolutionary need for the species to have internal development, simply because it is unnecessary and energy-consuming. It would thus be advantageous not to experience the same sounds the mother experiences, because with external development the mother does not have to spend energy and time (which she could have spent reproducing) carrying a baby internally. Additionally, external development is sometimes coupled with external fertilization, which allows for the organisms to release a large amount of eggs or sperm into the surrounding water to be fertilized, thus dramatically increasing the offspring’s chance of survival in an unstable environment (Campbell 1000). I did not consider much, however, the advantages of this disconnect between mother and child (present in external development). I thought David’s introduction of the drug thalidomide was an interesting example of how such close relations can actually be harmful. I suppose with internal development comes increased parental care, and, in the case of humans particularly, responsibility in our choices.
Like humans, kangaroo embryos develop in the lining of the uterus (Campbell 722). Approximately 33 days after fertilization, the baby kangaroo crawls from the exit of its mother’s reproductive tract to the pouch, where the baby will reside while it grows in size (Campbell 711). However, the pouch has little purpose in forcing the young to experience the same external stimuli as the mother; instead it serves as a protective space for development. Humans are unique in that they have highly sophisticated mental capacities—ones that are initiated as early as in the womb.
Diane Kuai (dianekuai@gmail.com)