Based on the similarity between living creatures (in life traits, cell structure, and DNA), scientists concluded that all living creatures are interconnected. There is ample evidence that complex species of living creatures evolved from simple species over millions of years. One of these guides is to find fossils of living creatures confined to ancient rock layers.
The first evidence of life on earth was found in the ancient rocks of 3.7 billion years old, and those single-celled creatures were simple. As we look at more recent rock layers, we also find more complex multicellular creatures. When we focus on vertebrates, we note that there is also a difference in the level of complexity of its structure and behavior. The more complex species appeared later on the globe: the first vertebrates that appeared were species of fish (ie, the "oldest" vertebrates). Later, amphibians, reptiles, and eventually birds and mammals appeared. Man, the most complex living creature, appeared again (that is, the human type is the "newest" type on the globe.
The first evidence of life on earth was found in the ancient rocks of 3.7 billion years old, and those single-celled creatures were simple. As we look at more recent rock layers, we also find more complex multicellular creatures. When we focus on vertebrates, we note that there is also a difference in the level of complexity of its structure and behavior. The more complex species appeared later on the globe: the first vertebrates that appeared were species of fish (ie, the "oldest" vertebrates). Later, amphibians, reptiles, and eventually birds and mammals appeared. Man, the most complex living creature, appeared again (that is, the human type is the "newest" type on the globe.
