This 3,700-Year-Old Olive Tree in Portugal Has Been Growing Since the Bronze Age (and Keeps Making Olives)
Posted: 28 Aug 2026, 20:11
Most trees retire after a few centuries. This ancient olive seems to have missed the memo, and it’s not the only one.
An olive tree growing in southern Portugal may have taken root around 1700 BCE — centuries before ancient Rome was founded and more than 1,300 years before Alexander the Great was born.
Known as the Oliveira do Peso, the tree grows at in Portugal’s Alentejo region. Its age has been estimated at roughly 3,700 years, making it the oldest olive tree so far dated in Portugal. One published figure puts it at 3,712 years old.
That lack of precision is almost always the case with ancient trees. Scientists can’t simply count thousands of annual rings inside an ancient olive tree. In fact, the very wood that would provide the best evidence of the tree’s beginnings has often disappeared centuries ago.
But this isn’t the only extraordinary olive tree in Portugal. For example, Oliveira do Mouchão near Abrantes is estimated at 3,350 years old. Another tree in Santa Iria de Azóia was put at around 2,850 years, while one in Monsaraz was estimated at 2,450 years. Now, a team of researchers at the University of Trás-os-Montes and Alto Douro (UTAD) has dated hundreds of these ancient trees, including specimens estimated to be more than 2,000 years old.
Here’s what they found.For many trees, age can be estimated by examining annual growth rings. Scientists can also use radiocarbon dating to determine when particular pieces of wood formed. Ancient olive trees make both approaches difficult.
As an olive tree grows older, parts of its central trunk can decay and disappear. Eventually, an enormous old tree may have a hollow centre, meaning the oldest wood—the material that could provide the strongest evidence of its age—is no longer there.
Olive trees also do not always produce neat, easily readable annual growth rings. Their growth can be asymmetric, and changes in water availability can produce structures that resemble annual rings even when they aren’t.A 2017 study demonstrated just how messy the problem can become. Researchers radiocarbon-dated multiple parts of a complete olive-tree cross-section and found that ring counts didn’t consistently correspond with the radiocarbon dates. The oldest datable wood in that particular tree was less than 200 years old.
Of course, that doesn’t mean the millennial olive trees are actually young. Rather, it shows that in very old olives, the original centre of the tree may have rotted away completely, leaving researchers without material from its earliest years.
There’s another complication. Olive trees can produce new shoots and trunks, so simply treating a huge circumference as a clock can be misleading. So then, how do you determine the accurate age of a tree when its oldest surviving wood may be gone?
Beginning in 2007, UTAD researchers and Oliveiras Milenares developed a non-destructive method designed specifically for old, hollow trees.
Instead of requiring researchers to cut down the tree or reach its missing centre, the approach uses dendrometric measurements — characteristics such as the trunk’s radius, diameter, height or circumference. For instance, they might measure its height and trunk circumference or diameter, using measurements taken at different points on the trunk. This data is then plugged in a mathematical model relating those dimensions to age.
The basic idea is relatively simple. If scientists understand how the dimensions of olive trees relate to their age, they can use the size and shape of a living tree to estimate its age—even when its centre is hollow, and the oldest wood cannot be examined.
This is particularly useful for ancient olives. Researchers can measure a living tree from the outside rather than destroying it to reach whatever remains of its oldest wood.
The method was patented and has since been applied to olive trees both in Portugal and abroad. This approach was used to estimate the age of the Oliveira do Mouchão at 3,350 years.The Oliveira do Peso, assessed in 2021, was estimated at more than 3,700 years old, with the reported age reaching 3,712 years. If this estimate is correct, the tree began growing around 1700 BCE—long before the Roman Empire existed.
The tree is about six metres tall, while its trunk has a circumference of roughly 10 metres. It is also not simply surviving as a hollow monument. The ancient tree continues to produce olives. According to the researchers, the ability to keep growing and fruiting may be one of the secrets behind the olive’s extraordinary longevity.
Olive trees have an unusual capacity for rejuvenation. An old section of trunk can die while other living portions remain capable of producing new shoots. In effect, the tree can replace parts of itself while the wider organism continues living.
“A piece of trunk, how old it may be, has the ability to sprout again,” José Luís Louzada, a researcher at UTAD, said in an interview.
This kind of extraordinary biological endurance has parallels elsewhere in nature, where some species have survived for millions of years with remarkably little change.
Its Mediterranean adaptations also help. Olive trees are well suited to hot, dry conditions and can reduce their activity during periods of severe heat and low humidity. Their slow growth and ability to survive difficult conditions can allow them to persist through enormous spans of time.
https://www.zmescience.com/science/news ... live-tree/
An olive tree growing in southern Portugal may have taken root around 1700 BCE — centuries before ancient Rome was founded and more than 1,300 years before Alexander the Great was born.
Known as the Oliveira do Peso, the tree grows at in Portugal’s Alentejo region. Its age has been estimated at roughly 3,700 years, making it the oldest olive tree so far dated in Portugal. One published figure puts it at 3,712 years old.
That lack of precision is almost always the case with ancient trees. Scientists can’t simply count thousands of annual rings inside an ancient olive tree. In fact, the very wood that would provide the best evidence of the tree’s beginnings has often disappeared centuries ago.
But this isn’t the only extraordinary olive tree in Portugal. For example, Oliveira do Mouchão near Abrantes is estimated at 3,350 years old. Another tree in Santa Iria de Azóia was put at around 2,850 years, while one in Monsaraz was estimated at 2,450 years. Now, a team of researchers at the University of Trás-os-Montes and Alto Douro (UTAD) has dated hundreds of these ancient trees, including specimens estimated to be more than 2,000 years old.
Here’s what they found.For many trees, age can be estimated by examining annual growth rings. Scientists can also use radiocarbon dating to determine when particular pieces of wood formed. Ancient olive trees make both approaches difficult.
As an olive tree grows older, parts of its central trunk can decay and disappear. Eventually, an enormous old tree may have a hollow centre, meaning the oldest wood—the material that could provide the strongest evidence of its age—is no longer there.
Olive trees also do not always produce neat, easily readable annual growth rings. Their growth can be asymmetric, and changes in water availability can produce structures that resemble annual rings even when they aren’t.A 2017 study demonstrated just how messy the problem can become. Researchers radiocarbon-dated multiple parts of a complete olive-tree cross-section and found that ring counts didn’t consistently correspond with the radiocarbon dates. The oldest datable wood in that particular tree was less than 200 years old.
Of course, that doesn’t mean the millennial olive trees are actually young. Rather, it shows that in very old olives, the original centre of the tree may have rotted away completely, leaving researchers without material from its earliest years.
There’s another complication. Olive trees can produce new shoots and trunks, so simply treating a huge circumference as a clock can be misleading. So then, how do you determine the accurate age of a tree when its oldest surviving wood may be gone?
Beginning in 2007, UTAD researchers and Oliveiras Milenares developed a non-destructive method designed specifically for old, hollow trees.
Instead of requiring researchers to cut down the tree or reach its missing centre, the approach uses dendrometric measurements — characteristics such as the trunk’s radius, diameter, height or circumference. For instance, they might measure its height and trunk circumference or diameter, using measurements taken at different points on the trunk. This data is then plugged in a mathematical model relating those dimensions to age.
The basic idea is relatively simple. If scientists understand how the dimensions of olive trees relate to their age, they can use the size and shape of a living tree to estimate its age—even when its centre is hollow, and the oldest wood cannot be examined.
This is particularly useful for ancient olives. Researchers can measure a living tree from the outside rather than destroying it to reach whatever remains of its oldest wood.
The method was patented and has since been applied to olive trees both in Portugal and abroad. This approach was used to estimate the age of the Oliveira do Mouchão at 3,350 years.The Oliveira do Peso, assessed in 2021, was estimated at more than 3,700 years old, with the reported age reaching 3,712 years. If this estimate is correct, the tree began growing around 1700 BCE—long before the Roman Empire existed.
The tree is about six metres tall, while its trunk has a circumference of roughly 10 metres. It is also not simply surviving as a hollow monument. The ancient tree continues to produce olives. According to the researchers, the ability to keep growing and fruiting may be one of the secrets behind the olive’s extraordinary longevity.
Olive trees have an unusual capacity for rejuvenation. An old section of trunk can die while other living portions remain capable of producing new shoots. In effect, the tree can replace parts of itself while the wider organism continues living.
“A piece of trunk, how old it may be, has the ability to sprout again,” José Luís Louzada, a researcher at UTAD, said in an interview.
This kind of extraordinary biological endurance has parallels elsewhere in nature, where some species have survived for millions of years with remarkably little change.
Its Mediterranean adaptations also help. Olive trees are well suited to hot, dry conditions and can reduce their activity during periods of severe heat and low humidity. Their slow growth and ability to survive difficult conditions can allow them to persist through enormous spans of time.
https://www.zmescience.com/science/news ... live-tree/