许多像康德这样的科学家建立了一个接近现代观点的血统概念;他的分析来自于对猩猩的研究，他声称猩猩有能力发展出与人类相似的结构。尽管他的理论目前与现代观点联系在一起;这个理论从来没有给出任何可能的机制来驱动生物体的变化。卡洛勒斯·林奈是另一位被认为是现代分类学之父的科学家，他的工作是对植物和动物进行等级分类。在他的理论中，他认为植物杂交是一种可以产生新的植物物种的过程。然而，他仍然支持与进化论相悖的创造论。伊拉斯谟·达尔文(查尔斯·达尔文的祖父)也是一位非常杰出的博物学家，他认为生命可能起源于一个共同的祖先。他的理论认为，废弃生物体的部分可能在其自身的机制中使这些部分生长或收缩。Jean-Baptiste Lamarck的进化论是另一个被现代实验证据所否定的中世纪理论。他的理论集中于这样一种观点，即生物体可以将其在自然生命中获得的某些特征遗传给后代。他认为有机体是不可改变的，而不是永恒的(Zirkle, 1941)。在达尔文发现自然选择之前，另一个关于进化的理论是托马斯·马尔萨斯(Thomas Malthus)在1766年至1834年之间提出的人口增长理论。根据这一理论，马尔萨斯声称，种群可以产生大量的后代，这些后代有能力在有限的资源上生存下来。他认为疾病、饥荒和贫穷是人口过剩的结果。他从不相信进化论，他认为自然灾害是上帝的愤怒。
Many scientists like Immanuel Kant established a notion of descent that was close to modern view; were he suspected that organisms may have originated from a common ancestor .His analysis emerged from studies of Orang Utang which he claimed had capacity to develop structures similar to those of man. Despite the fact that his theory is currently linked with modern views; the theory never gave any plausible mechanism that would drive changes in organisms.Carolus Linnaeus is another scientist who is viewed as the father of contemporary taxonomy in relation to his work of hierarchical classification in both plants and animals. In his theory, he viewed hybridization in plants as a process that could produce new plant species. However, he still supported the theory of creation that goes against the theory of evolution. Erasmus Darwin (Charles Darwin’s grandfather) was also a very illustrious naturalist who believed that life could have originated from a common ancestor. His theory states that the disuse of organism’s parts could in their own mechanism make the parts grow or shrink.Jean-Baptiste Lamarck’s theory of evolution is another medieval theory that has been discredited by modern experimental evidences. His theory concentrated on the idea that living organisms could transfer certain traits acquired during natural life to its offspring. He saw organisms as immutable and not permanent (Zirkle, 1941). Another theory about Evolution before Darwin’s Discovery of Natural Selection is the theory of population growth that was coined by Thomas Malthus’ between 1766-1834. According to the theory, Malthus claimed that populations could produce large number of offspring’s that could have capacity to stay alive on the available limited resources available. He viewed diseases, famine, and poverty to be the consequence of overpopulation. He never believed on the concept of evolution and he viewed the natural calamities as the wrath of God.