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Q: How do scientists know what early men looked like?

Krishna: Mainly through fossils and reconstruction technology!

Facial reconstruction is the process of recreating the face of an individual (whose identity is often not known) from their skeletal remains through an amalgamation of artistry, anthropology, osteology, and anatomy (4).

Palaeontologists use different techniques to remove fossils and skulls from rocks, earth and caves, depending on the properties of the rock and the composition of the fossils themselves. Some rocks like mudstone or sandstone are soft so it is quite easy to remove the fossils using simple hand tools. Other rocks, such as limestone, are more difficult to excavate. In those cases chemical methods using acids might be used to remove some of the rock.

A mandible and skull found at Nesher Ramla. Researchers suggest these specimens belonged to a previously unknown group of ancient hominins.

Credit: Avi Levin and Ilan Theiler, Sackler Faculty of Medicine, Tel Aviv University and Nature journal

Palaeontologists rely on artistic interpretation to reconstruct the appearance and behaviour. As a result, artists have taken an unusually central role in the scientific process of reconstructing.

Once fossil bones are extracted from the rock matrix they are treated with special glues to preserve them and protect them from damage (1).

Once the fossils are prepared and preserved, palaeontologists will study the remains in order to determine what type of species they belonged to and even what they looked like and how they lived (1).

Fossils are prepared and preserved, the bones are assembled and a detailed drawing or reconstruction is made of the remains. Experts are then used to recreate the possible physical appearance of the hominin.*

  • *hominin, any member of the zoological “tribe” Hominini (family Hominidae, order Primates), of which only one species exists today—Homo sapiens, or human beings. The term is used most often to refer to extinct members of the human lineage, some of which are now quite well known from fossil remains (2)

In most cases, a nearly complete skull is required to reconstruct facial features and a partial skeleton, especially with some limb bones, is needed to recreate height, body build and possible movement capabilities (leg bones essentially carry a skeleton so looking at the length, size and strength of these bones provides clues as to how a hominin moved). However, for fragile or incomplete remains, particularly skulls, CT scans (computerised tomography) can help create a virtual 3D image and then a plastic cast.

Muscles, tendons, fat tissues and skin are then added to recreate a living hominin. Fleshing out a skull or skeleton gives us a better understanding of how they looked and moved. Experts use marks on fossil bones to help them reattach soft tissues, as these reveal where the tissues attached and how strong they may have been. They also use educated guesses based on dissections of primates and forensic anthropology techniques, particularly for determining the thickness of tissues.

The growth of technology has introduced the digital age of hominin reconstruction. Computer programs blend cutting-edge wizardry with traditional techniques of drawing and sculpture to bring new realism to the movement and behaviour of our ancestors.

For instance, take the reconstruction of a creature that lived in east Africa about 1.9 million years ago. It is modelled on a famous skull known as KNM-ER 1470 which was found at Koobi Fora, Kenya in 1972. Hundreds of small, fossilised bone fragments were recovered before this work of reconstruction could begin (3).

The work to reconstruct KNM-ER 1470 (Homo rudolfensis) was begun by Meave Leakey. She had to sort through hundreds of fossil bone fragments but gradually reassembled a partial skull using more than 150 pieces.

Most of the skull was reassembled using the fragments collected from the discovery site but some parts of the skull were still missing. To reconstruct the entire skull, the missing parts were filled-in with modelling clay.

On some specimens the reconstruction of missing parts is a simple task that can be achieved by copying the features from one side of the body to the other. The task becomes more complex when an individual is missing an entire feature, such as the jaw or both cheek bones. In this case, it may be possible to copy the feature from other individuals of the same species. Otherwise, scientists have to rely on a detailed knowledge of anatomy to determine the appropriate shape and size of the missing feature.

The muscles and other tissues such as nose cartilage, fat deposits and the eyes can now be added. Marks on the bones show where the muscles once attached and also provide clues about how bulky these muscles were. The general size and shape of the nose can be worked out using the structure of the surrounding bones as well as the size and shape of the nasal opening. However, the exact details of the nose will remain unknown. The correct eye colour is also debatable.

Skin and hair are added to complete the reconstruction but these are often the most debatable aspects. Our ancestors’ skin colour and degree of hairiness is determined by comparisons with living primates.

Footnotes:

  1. Preparing fossils, reconstructing the past
  2. hominin | Definition, Characteristics, & Family Tree
  3. How do we know what they looked like?
  4. Forensic facial reconstruction - Wikipedia

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