What determines the gestation or egg-laying in species?

[Set the speed to 1.5 to make it comfortable to listen]
This is the first talk in the series - What is holding the Science from making a big leap forward?
From my research I found that the species which ingest the food after chewing adapted to gestation. The others which ingest whole or part of an animal evolved into egg-laying.
Gestation period of an animal, ranging from days to months, depends upon the size of a single bite compared to its size, wether it is chewed or ingested as a whole, and the type of food that was taken whether it is rich in nutrients or not.
Giant panda adapted to consume hard to digest bamboo. The excess internal heat in digesting the bamboo reduced its gestation period compared to a mammal of similar size. This resulted in the smallest newborn compared to the size of the mother. Similar to pandas, marsupials dietary habit include hard to digest food with shortened gestation period of few weeks. Wombat digestion takes around eight to 14 days and the gestation period is around 20 days. Therefore marsupials fall in the middle of egg-laying (reptiles) and longer gestation period (placentals), where they generate medium internal heat in digesting the food.
This research extends the theory of evolution from natural selection and genetic drift to dietary habits.
This theory also resolves the age old question of which one came first - Chicken or the egg?
It also points out few interesting slokas from Manusmṛti, an ancient Indian text, which indicate the same theory.
Chapters:
01:40 Beginning of the research
02:30 Relation between dietary habits and reproduction
04:10 Main points of the research
10:05 Relation between the ingested food and the gestation period
13:50 Where the research is published?
14:29 Chicken or Egg, which one came first?
16:40 Relevant slokas from Manusmṛti
20:01 Effect of cooked food on Homo sapiens
22:29 Dietary restrictions during pregnancy
25:05 Back to the beginning
26:50 End Note
29:22 Series - What is holding the Science from making a big leap forward?
29:33 What will be in the series?
Playlist: Research Publishing
• Research Publishing