Hello, Biology enthusiasts! Today, we'll go on a journey exploring molecular clocks, DNA sequence alignments, and how these concepts can help us understand the evolution of different species. Let's get started!

The molecular clock is a method used to estimate the time since two species diverged from a common ancestor. This estimate is based on the assumption that DNA mutations (i.e., changes in the base sequence of DNA) accumulate at a constant rate over time.

🕰️ Fun fact: This is like estimating how long someone has been cooking by looking at the amount of soup that has evaporated from the pot!

The more sequence differences there are between two species, the longer ago they diverged. But remember, the "tick-tock" of this molecular clock isn't always consistent - it can be influenced by factors like the length of the generation time, population size, selective pressure, and more.

🚀 To Infinity and Beyond: For example, fruit flies have a much faster mutation rate than humans because they reproduce more quickly. So, even though we've been around for a similar amount of time, fruit flies have more generations, and therefore, more opportunities for mutations.

Using these principles, scientists have estimated that humans split from our nearest living relatives about 4.5 million years ago! Meanwhile, common chimpanzees and bonobos split more recently, around one million years ago. Similarly, by analyzing mitochondrial DNA, we have estimated that our most recent common human ancestor lived around 150,000 years ago.

🌳 Family Tree Fun: Think of your family tree – the further back in time you go, the more different branches you find. It's the same with our genetic family tree!