We believe that the beginning of complex life on Earth was roughly 1.2 billion years ago. However, we have to reconsider it, thanks to the discovery of plants, which seems to be an oldest known samples of vegetative life. Seems that advanced multicellular life evolved much earlier than previously thought.

A team of paleontologists at the Swedish Museum of Natural History discovered in well – preserved rocks at Chitrakoot in central India plants-like fossils of 1.6 billion-year-old. By its look, it is most likely the sample of the red algae. This type of algae belongs to most primitive of the multicellular plants known as eukaryotic algae. Due to the presence of the pigment phycoerythrin, algae is red and represent one of the best witnesses of life history on Earth. Today these algae are mostly used in Asian cuisine and some of the most famous meals such as sushi containing its variations.

Red algae have pigment phycoerythrin which reflects red light and absorbs blue light. Because blue light penetrates water to a greater depth than the light of longer wavelengths, these pigments allow red algae to photosynthesize.

Discovered red algae embedded in fossils mats of cyanobacteria appear to be 400 million years older than earlier known samples of this form of life and reopen questions on the evolution of complex life. Using the synchrotron-based X-ray tomographic microscopy, scientists manage to see distinct inner cell structures and cell fountains. Despite the lack of DNA, these characteristics were helpful enough to identify and determine the age of fossils with high accuracy.

X-ray tomographic picture (false colors) of fossil thread-like red algae. Image credit: Stefan Bengtson; CCAL

Visible life on Earth has occurred during the Cambrian explosion 541 million years ago when major animal phyla appeared. Discovered plants fossils push the evolution of complex life back 400 million years. Although evidence is strong for now, scientists are careful. This type of discoveries has to have a certain degree of doubts as we are dealing with extremely old fossil materials. Until we find more similar fossils, this subject will partially remain controversial.