{"id":12789,"date":"2026-06-17T07:58:58","date_gmt":"2026-06-17T07:58:58","guid":{"rendered":"https:\/\/www.vedprep.com\/exams\/?p=12789"},"modified":"2026-06-17T08:02:38","modified_gmt":"2026-06-17T08:02:38","slug":"theories-of-evolution-for-iit","status":"publish","type":"post","link":"https:\/\/www.vedprep.com\/exams\/iit-jam\/theories-of-evolution-for-iit\/","title":{"rendered":"Theories of evolution (Lamarckism, Darwinism): IIT JAM 2027"},"content":{"rendered":"

If you are gearing up for the IIT JAM, you already know how massive the Theories of Evolution<\/strong><\/span>\u00a0unit is. Specifically, sections 1.1, 1.2, and 2.1 are where you want to score those clean, easy marks.<\/span><\/p>\n

Theories of evolution (Lamarckism, Darwinism) For IIT JAM<\/b><\/h2>\n

Let’s talk about the foundation of biology: the <\/span>theories of evolution <\/b>in the IIT JAM Syllabus<\/b><\/a>. If you look back at how we figured out how life changes, two major names pop up: Jean-Baptiste Lamarck and Charles Darwin.<\/span><\/p>\n

Lamarck came up with <\/span>Lamarckism<\/b>, which is basically the idea of the inheritance of acquired traits in Theories of evolution<\/strong>. He believed that if an animal changes its body during its lifetime to adapt to its surroundings, it can pass those brand-new traits directly down to its babies.<\/span><\/p>\n

Darwin, on the other hand, brought us <\/span>Darwinism<\/b>, or the theory of <\/span>natural selection <\/b>in the Theories of evolution<\/strong><\/span><\/b>. He skipped the idea of self-made physical changes and focused on the <\/span>struggle for existence<\/b>. Darwin said nature does the choosing: individuals born with helpful variations are simply more likely to survive, reproduce, and pass those winning genes to the next generation.<\/span><\/p>\n

Theories of evolution (Lamarckism, Darwinism) For IIT JAM: Lamarckism<\/b><\/h2>\n

Let\u2019s break down <\/span>Lamarckism<\/b> a bit more. Back in the early 19th century, Lamarck suggested that <\/span>acquired traits<\/b>\u2014things that happen to your body because of your environment, diet, or workouts\u2014could be handed down to your offspring.<\/span><\/p>\n

As per the Theories of evolution, <\/strong>Lamarck used giraffes to explain this. He thought giraffes used to have short necks, but they kept stretching upward to grab leaves from the highest branches. Over a lifetime of stretching, their necks got longer, and they passed those stretched necks down to their calves.<\/span><\/p>\n

Based on the Theories of evolution<\/strong>, Lamarckism has massive <\/span>limitations<\/b>. It completely falls apart when it comes to complex traits like eye color or intelligence, which depend on multiple genes. Plus, endless lab experiments have tried to prove this true, and they fail every single time. It also completely ignores the natural <\/span>variation<\/b> we see inside a population from the start, assuming everyone just changes the same way when things get tough.<\/span><\/p>\n

Theories of evolution (Lamarckism, Darwinism) For IIT JAM: Darwinism – Theory of Natural Selection<\/b><\/h2>\n

When Charles Darwin dropped his theory of <\/span>natural selection<\/b> in 1859, it completely turned biology upside down. Before him, most people believed in <\/span>fixism<\/b>\u2014the idea that every species was created exactly as it is and never changed a bit. Darwin challenged all of that.<\/span><\/p>\n

To really get Darwinism down for the IIT JAM, you need to know the core mechanisms of the Theories of evolution<\/strong>:<\/span><\/p>\n