6. Finding the Relationship Between Gravity and Evolution of Animals/Plants
If one day, a human can prevent him/her self from burning when alight- ing on the surface of the sun, under the effect of high gravity of sun, will stuck on the surface of sun like a sheet of pa- per. (Gamov, 1958)
I red this sentence in 1986 in a book titled Matter, Earth, and Sky written by George Gamow and concluded that live and death of animals are dependent on the STRENGHT of gravity. At first, I tried to establish a relationship by considering the skeleton and the amount of available food of the animals, but I faced with some obstacles. Later on I realized the importance of the circulatory system and thereby I explained on these basis the searched rela- tionship. I must admit that I was lucky that taxonomist had classified animals/plants according to the power of circulatory system of blood/fluid. A "battle" between gravity and blood/fluid circulatory systems has always existed because most of the force of the circulatory system is used to overcome gravity. If gravity increases, animals/plants are forced to get smaller or to strengthen their blood/fluid circulatory systems. Nature has used both methods. Since evolution (strengthening the blood/fluid circulatory system) requires a long time, as gravity increases, animals/plants initially retreat and minimize their bulks. But when the evolutionary process succeeds in providing them a more powerful blood/fluid circulatory systems, animals and plants immediately move forward overcoming the gravity by maximizing their body sizes. Stage by stage new and stronger blood/fluid circulatory systems resulted by the evolutionary process, aiding animals to overcome gravity and to increase their size. But with further increase of gravity, the larger sized animals reduced their sizes again (minimizing their bulk) looking for- ward to evolve toward new and more powerful pumping apparatuses. If we draw the graph of changes of animal/plant sizes in the past (Fig. 3a, Fig. 3b, Fig. 4),
Fig. 3. Animals and plants size evolution during the Geological Time. – a) Graph of the land animals’ size since ≈350 Ma ago to the Recent and Future. – b) Graph of the land plants’ size since 400 Ma ago to the Recent and Future. "Y" axis represents body size of the biggest species in each category at a specified time. "X" axis is the indicator of the time or indicates the amount of gravity at any time. Fall of the diagrams (decreasing slope) indicates that body size of species are getting smaller while the gravity is increasing. Force of the gravity on the blood/fluid circulatory system will prevail. Climbing of the diagrams (increasing slope) indicates that species are getting bigger as the result of evolution and as blood / fluid circulation system gets powerful. The force of blood / fluid circulation system will overcome the force of gravity. If the circulatory system of blood /fluid would not been evolved, diagrams had had only a decreasing slope and all animals and plants, under the effects of increased gravity, were small millions of years ago and now we couldn’t see any big animals and plants. Evolution of an animal or plant is possible under the effect of changing environmental conditions and selection of more adapted individuals to new situations by natural selection. The main factor driving the evolution of circulatory system is increasing of the gravity. Means, if the gravity had not been increased, the blood and material circulatory system was not needed for development. An intriguing prediction of future evolutionary process of animals and plants can be ipothesized according to these diagrams (new class and the type of their blood/ fluid circulation system). "New class" will evolve out of small mammals. The new class will have (4+1)-chambered heart. (4+1)-chambered heart = A four-chambered heart with a single-chambered heart (Subsidiary heart). Preparations this heart has been developed inside the body of modern mammals.
Fig. 4. Circulatory paths in vertebrates. Heart evolution of vertebrates has begun from 2-chambered hearts (fishes) and after passing 3-chambered phase (amphibians and reptiles), has reached to 4-chambered hearts (in mammals and birds). Adapted from Wikispaces (2012).
Fig. 5. The evolution of mammals: Mammals evolved at the first time by small bulk animals. Mammals have managed to overcame gravity by the aid of 4-chambered hearts and strong blood circulatory systems and making their bulks larger (as shown on figures). But during the time a gradual increasing of gravity occurred, mammals failed against greater gravity and had to minimize their bulks. The process of minimiz- ing the body size has continued up to now and will continue in the future Mammals will became gradually smaller and finally will have to crawl on the ground (like reptiles class that already had been forced to crawl). It is possible that in the future a new class of animals (among mammals) will occur having a stronger cir- culatory system that will be able to overcome gravity allowing the body size to evolve towards larger sizes again. If we compare a current dinosaur with a present elephant, it is a wrong comparison, because they belong to two separate classes. Also, if we compare the bulk size of a Baluchitherium with a Sauropod, such a comparison will not lead us to fact of increasing gravity. On the contrary, it will lead us the following: Reptiles class have been able to back the gravity more at their maximum point powerfulness, but mammals during their attack, have moved forward less than reptiles.
we could witness the subsequent rise and fall of the bulk sizes of different classes of animals/plants in the past. The graphs have been constructed by:
1. Considering the classification of animals/plants due to their power of blood/fluid circulatory system.
2. Superposing in the same figure the curves of the distinct classes.
3. Not to involving "rich people living in small houses" in these figures (because they cause confusion).
These graphs clearly show the increasing gravity.