About Lucy:

What species is Lucy and how does she relate to humans?
Lucy is an Australopithecus afarensis, a well documented group of early hominins. Fossil australopithecines show evidence of bipedalism and generally have relatively small brain size and body stature. This species may be ancestral to later Australopithecus species and early Homo.

Does the small size of Lucy’s brain mean she wasn’t smart?
No. Lucy’s brain size relative to body size is comparable to modern apes. Relative brain size is simply the size of the brain relative to the rest of the body. Brain size is not necessarily a diagnostic factor of intelligence. For example, Neanderthals had a larger body size than modern humans, which was an adaptation to colder climates. This means Neanderthals also had a larger brain size, but it doesn’t mean they were more intelligent than modern humans.

How did Lucy become a fossil?
After Lucy died, her bones settled into dirt and rocks, called sediments. She then was buried by many more layers of sediments. After a long time, the calcium in her bone was replaced with minerals from the surrounding soils. This process is called mineralization. It turns the bone into rock and preserves it for a long time.

How did Lucy move?
Lucy appears to have walked bipedally (on two legs) but also may have spent a lot of time in trees. Lucy arms are longer than her legs, which is characteristic of arboreal primates. Her finger and toe bones (phalanges) are curved like those seen in tree climbing (arboreal) hominins. But her hips and legs are more like bipedal hominins, such as modern humans, and the angle of her knee (valgus) suggests she walked upright on two legs.

What did Lucy eat?
Lucy probably ate fruits, plants, roots, seeds, insects, and possibly small animals. Scientists can hypothesize about an animal’s diet by looking at the cusp patterns and lines scratched into the surface of a tooth when an animal eats.

Why is Lucy so famous?
Lucy is the best preserved and most complete specimen of Au. afarensis, and dates to 3.2 mya.  About 40% of the entire skeleton was recovered.  Scientists have answered many questions about bipedal evolution by examining Lucy’s skeleton.

What sort of tools did Lucy use?
Stone tools have not been found at the same sites as Au. afarensis fossils. However, this does not mean Lucy did not use tools. In fact, Lucy probably used tools made of wood or reed that did not preserve over the millions of years of weathering and burial. It is also possible that she used unworked rocks and wooden sticks as tools, just as modern chimpanzees use today.

How did Lucy get her name?
Her official name is AL 288-1, but Lucy got her famous nickname from the Beatle’s song, “Lucy in the Sky with Diamonds.” The people who found her were listening to this song the night she was found. Lucy was also named Dinkinesh by Johanson. In Amharic, an Ethiopian language, Dinkinesh means “you are a beautiful, unique, special one.”

What is Lucy’s geologic age?
Lucy is 3.2 million years old. Scientists arrived at this date by testing chemicals, called Potassium-Argon and Argon-Argon, in layers of volcanic ash above and below the rock layer where Lucy was found.

Did Lucy speak and if so, what language did she speak?
There is no evidence Lucy had a spoken language, however, she may have been able to communicate in different forms. Primates are known to communicate in a variety of ways, such as gestures, facial expressions, and vocalizations. Humans communicate this way, too. For example, if you see a friend smile, it is interpreted as a sign of happiness.

How do scientists know Lucy is female?
Lucy’s pelvis bone is more similar in shape to that of a modern human female, and her fossilized skeleton is very small when compared to some other Au. afarensis fossils. Lucy’s small size suggests that she belonged to a sexually dimorphic species, a species in which the males have larger body sizes than females.

Did Lucy have any children?
It is possible Lucy had children, but no one knows for certain. Scientists usually look for marks on the symphyseal border of the female pubis bone for signs of childbirth. These marks, called parturition scars, look like pits on the surface of the pubis. The more pits, the more times the female was likely pregnant.  Lucy has some pitting on her pubis, but scientists are unable to tell how many children Lucy had.

How tall was Lucy?
Lucy was about 107 centimeters (3’6″) tall. Au. afarensis were sexually dimorphic, meaning that males were larger than females. A male may have been over four feet tall.

When and where was Lucy found?
Lucy was discovered on November 24, 1974, in the Hadar Formation in the central Afar region of Ethiopia.

How do scientists know Lucy was an adult?
Lucy had fully erupted wisdom teeth (or third molars) and her bones appear fully fused. Bones form in separate pieces and fuse (connect) together, and teeth erupt at different times in life as an animal grows. By the age of 35, most humans have fully erupted third molars and fused bones.

How did Lucy die?
No one really knows how Lucy died. Her skeleton looks different than it did when she died because it has been crushed by sediments for millions of years and then turned into a fossil. (See also “Did Lucy have any injuries, such as broken bones?”)

Did Lucy have any injuries, such as broken bones?
Scientists are not certain about any injuries Lucy might have had before she died. Her skeleton looks different than it did when she died because it has been crushed by sediments for millions of years and then turned into a fossil. (See also “How did Lucy die?”)

What type of house did Lucy live in?
Lucy didn’t live in a house like modern humans. Instead, Lucy most likely spent the night in trees or in caves.

What kind of habitat did Lucy live in?
Geologists have determined that Lucy lived around a large lake surrounded by trees. This would have provided easy access to water, plants and prey animals.

Who found Lucy?
Lucy was found by Donald Johanson and Tom Gray.

About Evolution:

Is evolution a fact or a theory?
Both! The genetic change over time in organisms, known as biological evolution, is an observable fact which can absolutely be observed in both living organisms and in the fossil record. The “theory of evolution” refers to the evolutionary mechanisms that may affect change within a population. A scientific theory is a hypothesis that has been tested to the extend that the observed results are reliably predictable and therefore considered true.

What is the difference between relative brain size and absolute brain size?
Absolute brain size is the actual size of the brain. Relative brain size is the size of the brain compared to the size of the entire body. Both absolute and relative brain size can help anthropologists differentiate between species.

What is natural selection?
One of the processes that must occur for evolution to exist is natural selection. Between individuals in a species there are always variations in the genetic material. Sometimes these variations give certain individuals a better chance at survival. The greater number of offspring from one individual, the greater the chance of changing the genetic structure of the population. After many generations, these small changes can add up to make an obvious difference. It has been proposed that these processes can lead to adaptation and eventually a new species over time.

What is adaptation?
An adaptation is a characteristic with a specific function that enables an organism to live in its environment and successfully reproduce. Adaptation is also a process in which organisms adjust to their environment. Selection pressure is the force that shapes specific adaptations. Adaptation is viewed as a response to problems set by the environment, and an adaptation can be morphological (i.e. physical) or behavioral.

What is gene flow?
Gene flow is the transfer of genes from one population to another within a single species.

Did humans come from monkeys?
No. All species are related to one another because they share genetic material inherited from a common ancestor, though some species are more closely related than others. For example, human and chimpanzees share over 98% of the same genetic material. Based on this fact, we can safely say humans and chimps shared a recent common ancestor that had ape-like morphology. This does not mean humans came from modern apes because apes living today also have evolved over millions of years since splitting from the last common ancestor with humans. The molecular data tells us that this ancestor lived between 5 and 7 million years ago. Another way to look at it, humans share nearly 85% of their DNA with mice. Eomaia scansoria was the last known common ancestor of both mice and humans and lived between 75 and 125 million years ago.

What is mutation?
Mutation occurs when changes are made to the genetic material. This can occur due to a copying error during DNA replication, or exposure to radiation, chemicals, or viruses. Mutation is typically random.

What is genetic drift?
Genetic drift is the accidental shift in allele frequencies in a population. It is caused by random chance as some individuals in a population leave behind a few more offspring than others. Its effects are most dramatic in small populations. The founder effect, an example of genetic drift, is seen in populations derived from a small sample of individuals who do not represent the genetic variation seen in the parent population. Genetic drift does not produce adaptations.

What is evolution?
Evolution is the process of change over time. Rocks, cars, computers, humans- everything changes over time. So when someone asks, “What is evolution?” the real question is “What is biological evolution?”

Biological evolution is descent with modification through genetic inheritance, i.e. parents pass along genetic traits to their offspring. Most importantly, biological evolution is a population process. Individuals are subject to selection and adaptation; populations evolve. Evolution may result in a new species or changes in an existing species. There are four mechanisms that act upon evolution: natural selection, random mutation, genetic drift, and gene flow. (More information on evolution can be found in the “What is Evolution?” teaching module.)

General Science:

What materials make up bone?
Bone is made up of both organic and inorganic components. Protein collagen provides the flexibility of bones while the mineral components of bones are mostly hydroxyapatites, formed primarily of calcium and phosphorus. Small amounts of sodium, magnesium, fluorides, and carbonates are also present. One-third of living bone is water.

What is a fossil?
A fossil is any anatomical evidence of past life. There are many different types of fossils, including body fossils where part(s) of the skeleton is preserved; trace fossils that preserve evidence of behavior such as footprints; and extraordinary fossils where soft tissues, such as skin, are preserved. Different types of processes are involved in the formation of different types of fossils.

What is a species?
A species is a group of interbreeding or potentially interbreeding organisms capable of producing fertile offspring. All offspring inherit genetic material from their parents, with individuals experiencing genetic mutations that make them slightly different from their parents. New species form when a population (i.e. daughter population) experiences genetic change due to environmental or genetic factors that inhibits successful reproduction with members of the ancestral (i.e. parent) population. This is commonly referred to as a speciation event. In cases where the species is extinct and known only from the fossil record, scientists can classify the fossil into a species based on traits that make fossil specimens unique from one another. In more recent years, scientists have used DNA analysis to differentiate between species.

Why do you use the term “hominin” while other anthropologists use the term “hominid”?
Both terms are most commonly used to describe a group that includes humans and our bipedal fossil relatives. The term hominid reflects a classification that groups humans and their bipedal fossil relatives in the family Hominidea to the exclusion of apes who are placed in the families Hylobatidae (gibbon and siamang) and Pongidae (orangutan, chimpanzee, bonobo and gorilla). The term hominin reflects a classification that groups humans and chimpanzees in the subfamily homininae and separates humans and their close fossil relatives into a separate tribe, the Hominini. Since the molecular data clearly shows a close genetic relationship between humans and chimpanzees, it is more appropriate to use the term hominin when discussing human evolution.

Do men and women have different numbers of ribs?
No. Most adult men and women have 12 pairs of ribs. However, there is variation in this number and some people may have an extra pair of ribs or an extra vertebra.

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