FACE TO FACE WITH

Leandro Sequeiros San Román, paleontologist

Leandro Sequeiros: “Here’s a thesis” (Emiliano Aguirre dixit)

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David Rabadà

As we approach the centenary of the renowned Spanish palaeontologist Emiliano Aguirre in 2025, it is fitting to interview someone who knew him with great insight and depth. Leandro Sequeiros San Román is such a person, whose own intellect illuminates any conversation with him. I must add that it was an immense pleasure to attentively listen to everything he shared.

Born in Seville in 1942, Siqueiros earned his degree in Geological Sciences from Granada in 1970, and four years later completed his PhD. His thirst for knowledge led him to a second degree in Theology in 2000, having already been a Professor of Palaeontology since 1983. He taught Palaeontology in Granada (1970-1975), Zaragoza (1975-1983), and Seville (1983-1988), among other prestigious positions. Siqueiros was also a Professor of Science Didactics in Úbeda (1986-1990), Research Methodology in Córdoba (1991-1997), and taught Philosophy of Nature, Philosophy of Science, Epistemology, and Philosophical Anthropology in Granada from 1997 to 2012.

His impressive academic career also includes membership on the Teaching Science Team of the Junta de Andalucía (1986-1997), being part of the Academy of Exact, Physical, and Natural Sciences at the University of Zaragoza since 2002, and receiving the Niccolo Stenone Medal from the Galleria dell’Accademia in Florence. Moreover, since 2021, he has been President of the Friends of Teilhard Association, and has authored over 150 books. Given such an illustrious career, it is only fitting to interview this Renaissance man to learn more about him and his dear friend, Emiliano Aguirre.

How did you first meet Emiliano Aguirre?

I believe it was in 1965, when Emiliano was 40 and completing his doctoral thesis on elephants, supervised by Miquel Crusafont. I was 23, studying Philosophy at the University of Comillas in Madrid. Emiliano came to our faculty to give a course on evolutionary topics. I still remember how much he impressed me.

How did your friendship develop from that point?

Two years later, in 1967, I was studying Geology at the University of Granada. Emiliano visited the fossil mammal sites in the Guadix basin. He was accompanied by Father Eduard Boné, a Jesuit scientist and Belgian palaeontologist. I gladly joined them on their visit. As soon as we arrived at the site, Emiliano bent down, picked up a large round fragment, and declared, “Well, this is an elephant’s patella”. That moment was memorable and marked the beginning of a great friendship. Shortly afterwards, Emiliano tried to convince me to write a thesis on fossil mammals, continuing the research he had carried out in the Granada, Guadix, and Baza basins between 1950 and 1955. However, I hesitated, as palaeontology in Granada at that time was mainly focused on ammonites.

But I imagine Emiliano persisted in convincing you

Indeed, he did. Between 1978 and 1979, Emiliano was my superior at the Department of Palaeontology in Zaragoza. By then, I was a Senior Lecturer, and he had become the first Chair of Palaeontology at the University of Zaragoza.

During that period, palaeontology and evolution were surrounded by scientific uncertainties. What was the difference in approach between Emiliano Aguirre and Miquel Crusafont in this regard?”

Both had differing views on evolution. The correspondence between Emiliano Aguirre and Miquel Crusafont, dating back to 1954, still survives. That year, Emiliano, aged 29, was excelling in his fourth year of a degree in Natural Sciences in Madrid (1950–1955), where he was a student of Bermudo Meléndez (1912–1999). Mr. Bermudo had been a Professor in Granada (1944–1949) and later a Professor in Madrid (from 1949 onwards). It was likely Bermudo who advised Emiliano that, if he wanted to specialise in fossil mammals and humans, he should turn to the leading expert of the time, Miquel Crusafont. Since the 1940s, Crusafont, accompanied by Villalta, had studied many fossil mammal sites in Catalonia and Castile. Crusafont had defended his doctoral thesis on fossil giraffes in 1950, and in 1952 had successfully organised the First International Course on Palaeontology in Sabadell, attended by Bermudo and Truyols among others. Bermudo suggested that Emiliano write to Crusafont to request an invitation to the second course, which took place in 1954, and to ask him to be his mentor and supervisor for his future thesis. Despite the 15-year age difference, the two soon got along, and Emiliano became a frequent visitor to Sabadell. However, Crusafont, perhaps shaped by the influence of certain French palaeontologists with a ‘vitalist’ and Lamarckian perspective, infused the Sabadell courses, his writings, and his lectures with the teleological and finalistic philosophy that defined his approach. He was likely inspired by the writings of Jesuit Pierre Teilhard de Chardin, which captivated Crusafont and led him to become a proponent of his ideas, especially those related to ‘deep orthogenesis’, aimed at a finalistic view of evolution that would align with his Catholic beliefs.

Faced with such an ideology, what did Emiliano do?

Out of respect, Emiliano chose not to contradict his Catalan mentor, who was a follower of Teilhard and a proponent of a finalistic worldview. However, Emiliano spoke English and had read the works of G. G. Simpson and many of the Anglo-Saxon palaeontologists who supported Neo-Darwinism and later the Modern Synthesis of Evolutionary Theory. Thus, even though his philosophical interpretation of evolutionary processes differed from that of Crusafont, Emiliano preferred to remain silent, to respect, and not to create conflict with his mentor.

“Emiliano, a young Jesuit [1959], took a risk with his presentation titled Philosophical and Theological Aspects of Evolution. In it, he embraced Darwin’s ideas”

In 1959, Emiliano gave an insightful presentation at the Darwin Centenary Congress. Can you explain what he presented and how it made an impact on the national scientific community?

Indeed, in 1959, when Emiliano was 34, the centenary of the publication of Darwin’s On the Origin of Species was celebrated worldwide. A significant congress was held at the University of Madrid, despite opposition from the Church and Franco’s regime. Emiliano, a young Jesuit, took a risk with his presentation titled Philosophical and Theological Aspects of Evolution. In it, he embraced Darwin’s ideas, asserted their compatibility with Christian faith, and declared his support for the Synthetic Theory of Evolution, championed by G. G. Simpson.

What were the consequences of that boldness for Emiliano?

It opened many doors for him in the scientific world but also sparked suspicion among Crusafont and others more resistant to these new ideas.

As both a palaeontologist and theologian, how do you reconcile the relationship between science and religion, which often seem to compete for truth?

It is not easy to synthesise the two. Much depends on what one means by “science” and “religion.” Science can be seen as a social construct, and religion as a personal experience of transcendence, where the clash of rationalities serves as a starting point, but the reconciliation of rationalities is our endpoint. Quoting Pope John Paul II’s letter to the Vatican Observatory on the 300th anniversary of Isaac Newton’s Philosophiae Naturalis Principia Mathematica (1687): “Science can purify religion from error and superstition, and religion can purify science from idolatry and false absolutes. Each can draw the other into a broader world, a world in which both can flourish”. (John Paul II’s letter to George Coyne, 1998)

You recently published a book on the relationship between three great Spanish palaeontologists: Truyols, Crusafont, and Aguirre. Could you summarise the essence of this project and its connection to Emiliano’s legacy?

Following the 1959 Darwin Congress, Emiliano Aguirre (1925-2021), Miquel Crusafont (1910-1983), Jaime Truyols (1921-2013) and Bermudo Meléndez (1912-1999) began collaborating on evolution and the fossil record. This culminated in the 1966 volume La Evolución, published by the Biblioteca de Autores Cristianos. This volume, with a provocative title at that time, was coordinated by the palaeontologists Miquel Crusafont, Bermudo Meléndez, and Emiliano Aguirre. The work brought together contributions from more than twenty authors, affiliated with diverse and contrasting branches of knowledge and ideological attitudes. In short, the volume La Evolución represented, in some way, a milestone on the path towards the normalisation of studies on the geoevolutionary theme in Spain, being, moreover, the first manual entirely written by authors from the country. It also symbolised an attempt to overcome the conflict between religion and science in a traditionally Catholic society such as Spain.

“Emiliano firmly believed that scientific literacy was essential for all citizens”

Emiliano was a strong advocate for the transmission of knowledge. You were part of a committee in the Andalusian Government that helped design the science curriculum for secondary students. What were Emiliano’s thoughts on transmitting science to our youth?

Emiliano firmly believed that scientific literacy was essential for all citizens. He held that a mature society needed to cultivate both intellectual and emotional skills, enabling individuals to critically engage with and rationally interpret the world around them.

And how were Emiliano’s classes?

He had little fondness for formal academic teaching. During our time together, he often delegated his teaching responsibilities to me. His vast knowledge allowed him to navigate classes with minimal preparation, leading to frequent repetition of content. Nevertheless, his true passion as a teacher and mentor flourished in the field. Upon his arrival in Zaragoza, he organised field days in Puebla de Valverde (Teruel). Months later, he exhibited remarkable enthusiasm and strength while teaching amidst the snowy landscapes of Medinaceli. That summer, he brought a group of eager students to Atapuerca, drawn by the allure of learning palaeontology outdoors. He possessed a unique ability to inspire budding palaeontologists, as demonstrated by the many theses he supervised—perhaps around a hundred.

Reflecting on your involvement in education in Andalusia, what did it encompass?

I had the privilege of collaborating with a team of twenty science experts for five years during the 1980s. This experience was immensely rewarding, and we endeavoured to share it with numerous science teachers across Andalusia. However, I believe our efforts fell short, as we encountered significant resistance to adopting an investigative teaching and learning methodology that would foster a shift in methodology, concepts, and attitudes. Many educators would assert, “I passed my competitive exams using a specific approach, and at my age, I cannot change my mindset”. Later, in 1994, we organised a Congress on the teaching of Geology in Córdoba, but, regrettably, few tangible outcomes emerged from it.

“I would tell him: Emiliano, rest in peace. The seeds you planted have borne much fruit“

Effort, in any field of knowledge, and in life itself, is a decisive factor for overcoming barriers and challenging situations. In 1994, you suffered a serious health setback, yet your mind remains active and clear. Did science and knowledge assist you in that arduous journey of personal recovery?

Indeed, in 1994, I suffered a second cerebral stroke; the first occurred in 1986. This second incident left me with motor disabilities. Fortunately, I have been able to lead a nearly normal life. My “neurons” are functioning well, and now retired, I dedicate my time to intellectual activities. Perhaps this book will help to provide a more comprehensive understanding of my work over the past 80 years: SEQUEIROS, L. (2023) https://www.bubok.es/libros/276435/50-anos-de-tarea-interdisciplinar-ASINJA.

To conclude, a personal question: if Emiliano were here today, what would you say to him?
I would tell him: “Emiliano, rest in peace. The seeds you planted have borne much fruit”. And inscribed on his tomb should be his favourite phrase from our field trips: “Here’s a thesis”. Emiliano always said this when a student discovered a fossil fragment, encouraging them to pursue further research. He was a true champion of inspiring students.

Source: educational EVIDENCE

Rights: Creative Commons