A first-of-its-kind study by an Israeli university seeks to uncover the information contained in ancient fruit trees
Apr 24, 2023
An ancient olive tree nicknamed “the tribal elder” grows in Wadi Zeitan, located in the northwestern Negev desert. For hundreds of years, this tree has kept numerous secrets, but they have now been revealed through a unique archaeological study.
Researchers from the University of Haifa and the Israel Antiquities Authority dug around the tree’s roots and dated the quartz crystals they found there. Before they were buried in the ground when the tree was planted, these crystals absorbed sunlight. Measuring the amount of energy remaining in them shows that the last time they saw daylight was 1,500 years ago. This gave an approximate date to the time the tree was planted and confirmed its old age.
Genetic tests of the tree showed that the rootstock was a Syrian olive tree, but a species unknown to science was grafted onto it. “We simply aren’t familiar with the historical world of fruit trees,” said Prof. Guy Bar-Oz, an archaeologist from the University of Haifa’s Center for Mediterranean History who served as the lead researcher of the study.
‘If we can read the trees, we will be able to write unknown chapters in the history of agriculture.’
Cuttings were taken from the tree, and they are now being grown in a rescue garden as part of a long-term experiment at the Volcani Center, which is Israel’s national institute for agricultural research and development.
“Who knows, maybe this olive tree will be a profitable cultivar in the future like present-day Barnea,” Bar-Oz said enthusiastically. “Millions of Barnea olive trees are grown in various parts of the world today, because it grows quickly and produces large fruit. But all the Barnea trees in the world originate from a single tree that was brought from the Kadesh Barnea region of Sinai by Shimon Lavie, the founder of the Volcani Institute’s olive section.
“We don’t know much about the history of this tree,” he continued. “The earliest known point in time is when Claude Jarvis, the then-Governor of Sinai, brought the tree from North Africa to Ain el-Qudeirat in northern Sinai around 100 years ago,” he said, using the modern name for the biblical Kadesh Barnea. “In our new study, we’re seeking to learn about the cultural heritage of fruit trees in Israel.”
Something went wrong
The study began seven years ago, after Bar-Oz read Jared Diamond’s book “Collapse,” which describes the collapse of societies in various places around the world. He noted that the collapse of the agricultural society that emerged in the Negev during the Byzantine era, from the fourth to seventh centuries C.E., wasn’t included, so he decided to start a research project inspired by the book.
“The Negev desert has a series of abandoned towns like Shivta, Halutza, Avdat and Nitzana that were once home to inspiring agricultural communities,” Bar-Oz said. “But at some point, something went wrong, and this entire network of communities collapsed and was entirely forgotten.”
UNESCO has declared the remnants of each of these towns as a World Heritage site, but much information about them remains a mystery.
“On the sign that explains the declaration [as a World Heritage site] posted at the entrance to Shivta, for instance, it says this was a Nabatean city on the Incense Route,” Bar-Oz said. “After a few years of work, I can tell you that Shivta wasn’t a city but a village, it wasn’t Nabatean but Byzantine, and that it wasn’t on the Incense Route.”
After excavating in Shivta in 2016 and 2017, together with Dr. Yotam Tepper from the Israel Antiquities Authority, Bar-Oz realized that in order to ascertain the source of the resilience shown by ancient Negev societies, one needed to understand how they shaped their environment so they could pursue an agricultural lifestyle in the desert.
‘In our excavations we found, for example, fish and shellfish originated from the Red Sea as well as from the Nile and the Mediterranean Sea.’
The usual argument is that the Byzantine settlements in the Negev collapsed following the Muslim conquest, climate change and various disease, like the Justinian plague. But according to Bar-Oz’s research, the collapse occurred at least 100 years before Arabs conquered the area. His studies also found no evidence of climate change or for the plague which could explain the collapse of Byzantine life in the Negev.
Bar-Oz surmised that the collapse was due largely to the breakdown of global trade routes. “People in the Negev excelled at growing vines and producing wine, which reached the entire Mediterranean basin. We discovered evidence for intensive commerce in raw materials and exotic foods, which reached the Negev from both the east and the west. In our excavations we found, for example, fish and shellfish originated from the Red Sea as well as from the Nile and the Mediterranean Sea. Such commerce directly indicates the high quality of life enjoyed by Negev inhabitants and their ties to other societies in the region.” Following the decline in the demand for wine, trade routes dwindled, and these societies fell apart.
An odd type of archaeology
In 2020, after the study of Nabatean settlements in the Negev ended, Bar-Oz planned to go on a long trip along the Silk Road, as part of a continuing study of the history and evolution of inter-continental trade routes. The Covid-19 epidemic foiled his plans.
“It was impossible to leave the country, and I had to reconfigure my plans. Instead of the planned mission, I signed up for a traditional dryland horticulture course focused on trees grown with no irrigation, where only water from precipitation is used, without storing water or channeling it to different plots. The course was given by Amit Pompan, from the kibbutz of Tziv’on. During the course, we created cuttings and grafts and built terraces. It was a very revealing experience that led me on a different journey, with the goal of studying and getting to know the history of traditional agriculture in Israel’s desert.”
Bar-Oz started out as a biologist, and most of his years in academia were spent as an archaeo-zoologist, focusing on studying animal bones from archaeological sites. His entry into the world of plants was a novelty for him. “There are groups in Israel studying the country’s fruit trees, but they consist mainly of botanists who focus on the taxonomic differences between varieties. They don’t study the ‘roots’ of trees, their cultural history. As an archaeologist, I can see that trees are part of culture.”
Bar-Oz admits that this is a somewhat odd type of archaeology, since archaeological digs were never done on living trees, which hold historical data. Previously, this type of information was not studied. “In Israel, and in the entire Mediterranean basin, fruit trees have been nurtured for thousands of years. If we learn how to read them and understand the information embedded in them, we can learn about unknown chapters in the history of agriculture. We want to characterize the architecture of the ancient fruit orchard and how it changed over time. This is pioneering work which has not been done before, here or overseas.”
Bar-Oz hopes that the current study will contribute to the study of the present and future, not just of the past, mainly in the context of global warming and the need to contend with harsh climates. “The Byzantines created sustainable agriculture in the Negev 1,500 years before the invention of drip-irrigation and desalination, and it was also an economically viable agriculture, moving beyond food security. Produce from the Negev reached far and wide.”
In the current study, which recently received a grant from the European Union’s ERC Advance grant, Bar-Oz hopes to find additional unknown species, forgotten over time, such as the species of olive he discovered. He also wants to document heritage orchards that are vestiges of traditional agriculture with roots reaching back to ancient times. He says that they tell “an important chapter in the cultural history of this country.”
As part of the study, which will take place in the Arava region, in the Negev mountains, in the southern coastal plain and the Judean coastal plain, Bar-Oz’s team, headed by Dr. Meirav Meiri, conducted a genetic analysis of vine species. High-quality DNA was extracted from archaeological grape seeds found in Avdat. The DNA sequencing from these seeds enabled a comparison to the closest living cultivars. One of the old grapes was found to be identical to one known today as “Be’er Palmachim” and to another species which now grows only in Lebanon and Greece, called “Syriki.”
“In Israel, this vine has gone extinct in cultivated vineyards. We now plan to revive this vine in Avdat and return it to its origins. Following restoring it in the Negev, we’ll be able to study if the traditional vine has unique properties giving it resilience in dry desert conditions,” says Bar-Oz. The results are described in an article that was published last week in the prestigious journal Proceedings of the National Academy of Sciences (PNAS).
Bar-Oz notes that while many animals and plants multiply by sexual reproduction, so that their genetic variety increases over time, fruit trees reproduce mainly through asexual (vegetative) reproduction. Their genetic characteristics can be fixed and not changed for many generations. “If you liked the grapes in my yard, I’ll give you a cutting, a branch you can plant in your yard, through which you can grow exactly the same vine I have. Therefore, you can find in the genetics of srchaeological seeds found in excavations type of fruit trees that still did not change to the present day. You can look at the history of fruit trees through their genetics, and that way write a new chapter on the geographic history of trees and the people who spread them.”
Along with the olive and vine, Bar-Oz plans to study the history of date palms that remnants of their past agriculture are spread across the Arava and Dead Sea . “You go to Ein Zik, in the Negev Highlands, for example, where there is a reserve of more than 600 date palm trees growing in clusters near springs. What are they doing there? When did they arrived? What cultivar are they? Did they originate from North African (Morocco) or Middle Eastern (Iraq) cultivars? How did they get there and when? No one has looked into that.”
Towards the end of our conversation, Bar-Oz asks to add a few words. “For several weeks now, I’ve been walking around with a shirt that says ‘No academia without democracy.’ This study is an example of that. Myself and 15 other researchers in Israel received the prestigious and most competitive grant from the European Union.
“Little Israel is ranked third in the number of people awarded these grants this year, after Germany and Britain. We are there due to the freedom to create and to think. Part of the considerations in giving this grant are how risk the study is, with the assumption that a high risk can lead to a high gains and scientific breakthrough. Israeli scientists are prominent in global research for, among other reasons, the place we develop in. I, for example, studied zoology and now I research botany. The possibility of breaking barriers is part of the pluralism of Israel’s academia, and that has brought it to the forefront of global science.”